NOTE: You cannot see privileges that you do not already have. If you do not have this privilege assigned to your profile, you will not be able to add/remove it from others.
To add/remove the privilege to remove signed agreements in ISN, you will navigate to Admin -- User Administration.
Find the user you want to modify and go to Actions -- Edit
Scroll down to your "Privileges" section and look for the privilege "Remove Signed Agreements"
Check/uncheck the box, be sure to SAVE!