A quick way around this would be to accept all track changes first and then use the Delete All Comments option.
NOTE: The Document Inspector notes at the bottom of the dialog box that some changes cannot be undone. Revise documents with Track Changes and Comments in Word 2007, a training course, will teach you how to review, accept, reject, and hide tracked changes in Word 2007, and along the way you get to practice. Learn how to replace existing and future user names connected to all Track Changes comments and edits with the default label Author. How do i permanently remove track changes from a word document mac Select 'Accept All Changes in Document' from the 'Accept' options.
