Need help to a very big problem

Alright, so I have a friend who made a group page on FB and thought it would go somewhere, however, someone has now hacked the page, installed himself as admin AND is now basically utilizing that page to harass a friend of mine. Is there a way I can either hack him off as admin OR what would I need to do since I already reported his account and I have blocked him. I even encouraged my friend to block him and I am now starting to think this will become something WAY more worse than what it’s worth. Please, anything will help.