In PowerPoint, you can add, reply to, or delete comments when working with others on a presentation.
Add a comment
Select Review > New Comment.
Or select New if the Comments pane is open.
In the Comments pane, type your message in the box and press Enter.
Note: Keep in mind that it's possible for others to edit your comments. Comments in Office documents are stored in the file, so anyone with edit access to your file can edit your comment.
View and reply to comments
Select the comment icon on the slide.
The Comments pane will open and you can see comments for that slide.
Select Reply to respond to a comment.
Select the Next or Back buttons to go between comments and slides.
Delete a comment
In the Comments pane, select the comment you want to delete and select the X.
On the slide, right-click the comment icon and select Delete Comment.