Depending on how you do permissions you can remove administrator from the access list either in active directory or NTFS permissions. Just log on as administrator and right click on whatever you wish to remove permissions from and share options and remove the administrator. Just be sure that someone has full control over the folder to make changes and perhaps make a back up account that has full access in case something happens to the owner of that account. The only thing is if he has full domain admin controls like mentioned he could potentially revert this change. So if it is a trust issue you probably look into replacing this guy or knocking him down on the permissions list to power user not administrator.