This is necessary if changes are needed to the review packet or the manager summary.
Navigate to Admin > Performance > Reviews.
Select the review cycle that you need to action in.
Enter the Share phase and find the reviewee who needs to have their packet unshared.
Select the ellipsis (...) to the far right of the reviewee's name and then select Reopen summary remarks from the drop-down menu.
The reviewee will have a preview of their review results, but will lose access to their summary. Their manager will be able to edit and re-share their post-review summary (if applicable).