Redact a PowerPoint before it goes to AI

A slide deck carries far more than the slides. To redact a PowerPoint before it goes near ChatGPT, Claude, Gemini or Copilot, work on a copy and take out, in this order: the hidden slides, anything parked off the edge of a slide, the comments, the speaker notes, the text in the slide master and footer, the alt text on pictures, and the spreadsheet stored behind each chart. Then fix the names on the slides themselves.

Covering a name with a black shape, or shrinking it until nobody can read it, does none of that. The file keeps the words.

This guide is for the office manager preparing a client review, the payroll lead with a quarterly summary and the solicitor with a training session built from real matters: anyone who wants an AI tool to tidy, shorten or rewrite a presentation. Whether client data in a chatbot is a problem in the first place, and why, is answered in our guide on client data and ChatGPT.

Some related jobs live elsewhere. A letter or report needs the Word method, a spreadsheet has its own traps, and the Irish identifiers worth removing from any file are listed in what to take out before AI.

How to redact a PowerPoint: most of it is not on the slides

PowerPoint is designed around the person presenting. The audience sees the slides; the presenter sees the slides plus a script, a few spare slides kept back in case someone asks, and the comments colleagues left while the deck was being prepared. All of that is saved in one .pptx, because the presenter needs it on the day.

When the same deck is handed to an AI tool, there is no presenter view and no audience view. There is only the file, and every one of those layers is text in it.

Layer	Where you see it in PowerPoint	Who usually forgets it
Speaker notes	the Notes pane under each slide	whoever wrote the talk
Hidden slides	a slash through the slide number	whoever kept a backup slide
Comments	the Comments pane	the reviewer
Slide master and footer	View, Slide Master	whoever set up the template
Chart data	Chart Design, Edit Data	whoever pasted the chart

Sources: Microsoft Support pages on speaker notes, hidden slides, the slide master and charts.

What the AI tool is given

Uploading a deck and pasting its text are different routes, and both carry more than the slides show. Copy the words off one slide and you get that slide’s text; upload or export the whole file and the other layers can travel with it.

Anthropic’s help centre, in its July 2026 list of document types Claude accepts, names PDF, DOCX and XLSX but not PPTX, so, going by that list, a deck headed there travels as a PDF or as pasted text. That export has choices of its own, covered in the step list below and in our PDF guide. Copilot works inside PowerPoint itself, which raises a different question altogether, one that our Copilot guide takes up.

A test deck, unzipped

To check what a presentation carries, we built one. It is a payroll review for an invented accountancy client, three slides long. On screen, slide one is a title and two harmless lines, slide three is a bar chart of overtime by team, and slide two does not appear in the slide show at all. Apart from a small footer, nothing a viewer would see names anyone.

Around that, we placed seven things a busy office puts in decks without thinking:

• a speaker note asking a colleague about an employee’s PPS number;
• a hidden slide with a client’s name and IBAN;
• a comment asking to take an employee’s sick leave out of the slide, signed by its author;
• a line of text in the slide master, so it sits behind every slide;
• a footer saying who prepared the deck;
• alt text on a picture, naming the person in the photo;
• a text box dragged off to the right of the slide, holding an Eircode.

And the chart on slide three is built from a small embedded workbook that holds an employee’s name and PPS number in columns the chart never draws.

All the details are made up and chosen so no real person could hold them. The PPS number is the all zeros one with a check letter, the IBAN is the specimen published for Irish IBANs, the Eircode uses A00, a routing key that does not exist, and the email domain is reserved for examples. More on what makes a PPS number sensitive is in our PPSN guide.

What a few lines of Python printed

We then opened the file the way a program does. A .pptx is a zip file holding a set of XML parts; Microsoft’s format documentation gives every slide an XML file of its own and keeps comments in a separate part. Our script is about seventy lines of Python using only its standard library, with no PowerPoint and no tool of ours involved. It listed thirty parts and printed the text in each.

Eight hiding places, one file, and the script did not have to look for any of them: they are simply parts of the package. It is also why what follows goes layer by layer rather than slide by slide. A comment about sick leave counts as health data, and that puts the Article 9 rules on top of everything else.

Speaker notes, the script that travels with the file

In Microsoft’s words, the Notes pane is “the place to store talking points that you want to mention when you give your presentation”, and while you present they show on your monitor, not to the audience. That second half is the trap. Invisible to the room is not the same as absent from the file: each slide with notes has a notes part of its own inside the package.

Notes are also where the most specific details end up. A slide says “Two open payroll queries”; the note under it says who they are about, what the employee told HR and which number to ring. Our test note did exactly that, with a colleague’s name and a PPS number in one sentence.

Notes also outlive the meeting they were written for. A deck presented in March is reused in June with the old script still underneath, and nobody rereads a talk they have already given. In a clinic, the notes under a case presentation are often the one place a patient is named, which our guide for practices deals with.

Clearing every note at once

On Windows, the Document Inspector lists presentation notes as a category it can find and remove, and it lives behind the File tab: choose Info, and Inspect Document sits under Check for Issues. Tick Presentation Notes, choose Inspect, then Remove All. Microsoft asks you to do this on a copy, because what the inspector removes cannot always be restored. If you still want the talk for yourself, save the notes somewhere else first.

On a Mac there is no inspector page from Microsoft, so open View, Normal, click into the Notes pane of each slide and delete the text. It is slow, which is a good reason to check each note as you go: a note you read is a note you understand before it leaves.

Hidden slides and objects parked off the edge

Hiding a slide is the presenter’s way of keeping an answer in reserve. Microsoft’s page on it is blunt: the slide stays in the presentation and is skipped only when the slide show runs. On Windows its thumbnail gets its number struck through with a slash; on a Mac, a small “no” symbol.

To bring one back, right click it in the thumbnail pane and choose Unhide Slide; to get rid of it, right click and choose Delete Slide. In the version headed for an AI tool, delete. Our hidden slide held a client’s name and an IBAN, and the script printed both on the same pass as the title slide. Bank details and the other Irish identifiers worth removing are gathered in our guide on what to take out.

Off the slide, and formatted to be invisible

Objects can also sit on a visible slide without being seen. People drag a text box past the edge to keep a reminder handy, or set a shape to no fill and no line. Microsoft’s Document Inspector page names both as categories of their own: content formatted as invisible on a slide, and content off the slide, which it describes as objects not immediately visible because they were dragged off.

The Selection pane shows everything on a slide in one list, whether you can see it or not. On Windows it is under Home, Arrange, Selection Pane, or Alt+F10; on a Mac, under Shape Format. Go through it slide by slide in the copy, and delete what does not belong. Our stray text box, with an Eircode in it, was listed by the script as sitting beyond the slide’s right edge.

Comments and the names pinned to them

Comments are where a deck gets argued over. They also carry names in two ways: the person the comment is about, and the person who wrote it. Microsoft’s description of the file format says each comment is tied to its author through an author ID, and the list of comment authors, with each name and initials, is a part of its own. A Word draft stores reviewers’ names the same way, so its comments and tracked changes need clearing too.

Our test comment read “Take Aoibheann’s sick leave out of this slide”, and the script printed it together with the name of the colleague who left it. Two people, neither of them visible on any slide. Word documents do the same with tracked changes and comments, as our Word guide shows, and a file’s author fields are covered under metadata.

To remove one comment, open the Comments pane, select it, choose More thread actions (the three dots) and then Delete thread. On Windows, all of them go at once from Inspect Document: tick Comments before inspecting, then press Remove All. Read the thread before you delete it: comments are where the one detail that really matters tends to get typed, and the slide may need changing because of it.

What the slide master and alt text carry

The slide master is the template behind the slides. Microsoft’s page on it says that when you edit it, every slide based on that master picks up the change, which is exactly why people put a client name, a “Confidential: prepared for” line or a logo there.

The master opens from View, Slide Master; check it and every layout listed beneath it. In our test file the master carried a client’s name, on no slide as such and behind all of them.

Templates also get reused: a deck built from last month’s client presentation can still carry that client’s name in a layout nobody has opened since. The file’s properties, where the author and company are recorded, are another matter, and the metadata guide deals with them.

Footers

Footer text is set from Insert, Header & Footer, where a Footer box applies a line to one slide or to all of them. Offices put a preparer’s name, a client code or a file reference there. Clear the Footer box and choose Apply to All in the copy you are sending.

Alt text on pictures

Alt text exists so that someone using a screen reader hears what a picture shows, and Microsoft points out that PowerPoint can write a description for you.

That is good practice for accessibility, but a description such as “Photo of the client at the Cork office” is a sentence naming a person, stored with the picture. Right click each picture, choose View Alt Text, and rewrite any description that names someone. Better still, ask whether the photo needs to go to the AI tool at all.

Charts that bring their own spreadsheet

A chart in PowerPoint is not a picture of numbers. When it is created in PowerPoint or pasted from Excel with one of the Embed Workbook options, the data comes along as a small workbook stored inside the presentation. The Microsoft Support page on putting Excel data into PowerPoint warns that a large embedded Excel file will inflate the presentation, which only happens because the file is inside it.

On screen, our test chart showed just two bars, Team A and Team B. The workbook behind it also held an employee’s name and PPS number in columns the chart never used, and the script printed them from the embedded .xlsx. Everything our Excel guide says about hidden columns and sheets applies to that workbook too.

How the chart got there	What the .pptx keeps	Before it goes to AI
Inserted in PowerPoint	a workbook with its data	Edit Data, delete extra rows and columns
Pasted with Embed Workbook	the source workbook	paste again as a picture
Pasted with Link Data	a link back to the source workbook	paste again as a picture
Pasted as Picture	an image only	check what the labels say

Sources: Microsoft Support, Copy from Excel to another Office program, and Insert and update Excel data in PowerPoint.

What the Document Inspector leaves in

Microsoft’s inspector page lists embedded files and objects, charts among them, as things it finds but cannot remove. So a clean inspection report can still leave a whole workbook inside the file. Replace each chart with a picture of itself: cut it, paste it back, and choose Picture under Paste Options. The picture option, in Microsoft’s words, gives a chart that cannot be edited or updated, which for this copy is the point.

If the AI tool needs to work with the numbers, keep the chart but open Edit Data and delete every row and column the chart does not draw. Then read the chart title and the axis labels, which are text in the file like any other.

Clearing a presentation in PowerPoint, in order

This is how to redact a PowerPoint in practice, and the order keeps each step from undoing the one before. Menus are those of PowerPoint in Microsoft 365 for Windows, in Microsoft’s English wording.

1. Save a copy under a new name and close the original. The DPC’s 2021 redaction guidance insists on working from a copy, and Microsoft asks for one before its Document Inspector is used.
2. Unhide every hidden slide, read it, and delete the ones the AI tool does not need.
3. Open the Selection pane on each slide and delete anything invisible or off the slide.
4. Read every comment, act on it, then remove them all.
5. Read every speaker note, move anything you need to keep into your own file, then clear the notes.
6. Open View, Slide Master and clear names from the master and layouts; clear the footer.
7. Check the alt text on each picture, and crop or delete photos and screenshots that show people or identity documents.
8. Replace each chart with a picture of itself, or empty its data sheet down to what the chart draws.
9. Change the names that remain on the slides, as the next section explains.
10. Run Inspect Document, use Remove All on every category you want gone, and read the report of what it could not clear.

Step 7 matters more than it looks. The DPC adds that a search cannot reach text held as an image, a photographed certificate being its example, so a screenshot of an email pasted onto a slide will not show up in any search you run, and nor will a photographed driving licence. Look at every image with your own eyes. If you upload a slide as a picture to ask a chatbot about it, it is kept like any photo, as our guide to AI image uploads explains.

On a Mac

Microsoft’s inspector page does not cover PowerPoint for Mac. Steps 1 to 9 work the same way, with the notes cleared slide by slide and the Selection pane under Shape Format. File properties, such as the author and company, are handled in the metadata guide.

Exporting to PDF instead

Turning the presentation into a PDF feels like a clean break, and it can be, but the dialog decides what goes in. On Windows, the Options button offers to publish slides, handouts, notes pages or the outline, to include hidden slides, to include comments and ink markup, and to include document properties.

PDF option on Windows	What it adds to the PDF
Publish what: Notes pages	the speaker notes under each slide
Include hidden slides	the slides kept back
Include comments and ink markup	the comments and their authors
Document properties	author, title and the like

Source: Microsoft Support, Save PowerPoint presentations as PDF files. On a Mac, notes pages and hidden slides are not offered.

With those left unticked, what reaches the PDF is closer to what the audience saw. It is still a PDF, with the traps of its own that our PDF guide sets out, so open it and search it before it goes anywhere.

One person, five spellings across a deck

Finding every mention of a person in a presentation is harder than in a letter, because a deck is written in fragments. The DPC’s redaction note, published in August 2021, cautions that a search turns up only the words you type into it, and gives the case of one person who might appear as “Seán”, “Mr Murphy”, “the Appellant’s neighbour” or just initials.

A deck multiplies that. The title slide says the full name, a table uses the surname, a note says the first name, a comment uses initials and a chart label uses a staff code.

Replace, then search for what is left

The DPC suggests swapping redacted text for a visible marker like [REDACTED], so a reader can tell where something was taken out. In a deck meant for an AI tool, a role is often more useful than a blank: “the client”, “employee A”, “the payroll contact”.

Use Replace on the Home tab for each spelling you know, then search the copy for the first name, the surname and the initials separately. Check SmartArt graphics and chart labels on their own, since you edit them in panes of their own, and look hard at any text that is really a picture.

Codes you invent are still linked to people while you keep the list that decodes them, which makes the result pseudonymised rather than anonymous, as our pseudonymisation guide explains.

Nonimo on a payroll review deck

Nonimo does the taking out for you. Select the .pptx, in File Explorer on Windows or Finder on a Mac, and press your Nonimo shortcut: the clipboard then holds the text of every slide, hidden slides included, and the speaker notes, with the personal details swapped for labels. You paste that into the AI tool, and when you paste its reply back, Nonimo turns the labels into the names again. The shortcut gives you text, and dropping the file into Nonimo’s window lets you download the masked copy in the same format, a .pptx; on a Mac the save dialog opens in the original’s folder.

We tested it on 28 September 2026, on a three slide version of our deck, using the Nonimo app:

Part of the deck	In the file	What the AI tool gets
Slide 1	Client: Dearbhla Ní Chuirc · Email: dearbhla.nichuirc@example.com	Client: [PERSON_1] · Email: [EMAIL_1]
Slide 2, table	Cathal Mac Lochlainn · 0000000W · Resolved	[PERSON_2] · [REFERENCE_1] · Resolved
Slide 2, table	Aoibheann Mulqueen · aoibheann.mulqueen@example.org · Open	[PERSON_3] · [EMAIL_2] · Open
Slide 3, hidden	Client: Fionnán Dervan · IBAN: IE29AIBK93115212345678	Client: [PERSON_4] · IBAN: [IBAN_1]
Notes, slide 2	Contact name: Niamh Cronnelly · Mobile: 087 000 0000	Contact name: [PERSON_5] · Mobile: [PHONE_1]

Details made up for this guide, Mac release. Empty cells left out; the table headings and the first line of the note came through unchanged.

Tip: put a name after “Name:” or “Contact name:” in your notes and Nonimo picks it up straight away. More on how Nonimo works is on our security page.

A second reader for the finished deck

Whoever cleaned the deck knows what it is supposed to say, which makes them the worst person to check it. Hand the copy to a colleague for five minutes with these questions:

1. Does the slide count in the thumbnail pane match the slide show, with no slashed numbers left?
2. Is the Notes pane empty on every slide?
3. Is the Comments pane empty?
4. Does View, Slide Master show any name?
5. Does any chart still open a data sheet with Edit Data?
6. Does anything on the slides, a role, a town and a date together, still point to one person?

The sixth question is the one no menu answers, and in a small practice it is often the one that matters: “the payroll query from the Galway branch in March” can name someone without naming them. Our list of Irish identifiers covers these combinations in more detail.

Offices that send decks to AI tools every week tend to put this check in writing, alongside the rest of their rules for AI. Accountants and solicitors pass more client decks around than most, and our page for accountants in Ireland, like the one for solicitors in Ireland, shows how Nonimo fits their work.

Sources

• Microsoft Support, Remove hidden data and personal information by inspecting documents, presentations, or workbooks. PowerPoint categories: comments, document properties, invisible content on a slide, content moved off the slide, presentation notes; embedded files or objects found but not removed; Inspect Document under Check for Issues on the Info page; work on a copy. support.microsoft.com
• Microsoft Support, Add speaker notes to your slides. The Notes pane for talking points; notes visible on your monitor but not to the audience. support.microsoft.com
• Microsoft Support, Hide or show a slide. A hidden slide stays in the presentation; Hide Slide and Unhide Slide; the slash and the “no” symbol. support.microsoft.com
• Microsoft Support, Use the Selection pane to manage objects in documents. Home or Shape, Arrange, Selection Pane, or Alt+F10; Shape Format on a Mac. support.microsoft.com
• Microsoft Support, Add, change, hide, or delete comments in a presentation. More thread actions, Delete thread. support.microsoft.com
• Microsoft Support, What is a slide master in PowerPoint? View, Slide Master; edits reach every slide based on that master. support.microsoft.com
• Microsoft Support, Insert or change the slide numbers, date, or footer for on-screen slides in PowerPoint. Insert, Header & Footer; the Footer box; Apply to All. support.microsoft.com
• Microsoft Support, Add alternative text to a shape, picture, chart, SmartArt graphic, or other object. View Alt Text; what screen reader users hear; generated descriptions. support.microsoft.com
• Microsoft Support, Copy from Excel to another Office program. Embed Workbook, Link Data and Picture paste options; a pasted picture cannot be edited or updated. support.microsoft.com
• Microsoft Support, Insert and update Excel data in PowerPoint. A large embedded Excel file inflates the presentation. support.microsoft.com
• Microsoft Support, Save PowerPoint presentations as PDF files. Publish what (slides, handouts, notes pages, outline view); include hidden slides; include comments and ink markup; document properties; the Mac limits. support.microsoft.com
• Microsoft Learn, Structure of a PresentationML document. A separate XML file for each slide; comments in their own part, each tied to an author; the comment authors part with names and initials; renaming .pptx to .zip. learn.microsoft.com
• Claude Help Center, Upload files to Claude (updated 23 July 2026). The document types listed: PDF, DOCX, CSV, TXT, HTML, ODT, RTF, EPUB, JSON, XLSX. support.claude.com
• Data Protection Commission, Redacting Documents and Records (August 2021). Presentation programs among the files holding more than appears on screen; search functions and the “Seán” and “Mr Murphy” example; text in image format; work on a copy; replace with [REDACTED]. dataprotection.ie