The ability to delete pages from an existing proof is necessary for efficiency. Example: I have a 60 page image document that 5 teams need to review. The second stage discovers two duplicates after making comments on all 60 pages. As a proof owner I'd like to delete the two duplicate pages.
1. This ensures the rest of the stages see a correct document
2. This also ensures the next rounds will be able to auto-compare perfectly, as they will not have the dupes.
3. I can't delete the proof and re-upload without losing the 60 pages of comments - it's too much work to recreate them.