Well. Depending on the OS of the account. You may have to: IOS: Receive the security information of the apple iD. Then also remove of all emails and phone numbers. (A good idea would be to change the apple I'D itself to one of your emails) or Android: Receive all google information including; Gmail, google play, clash and recovery emails to the gmail attached to clash. For this you're advised to change the google password and security information to your own. I'd recommend you to two step verify for gmail. Another thing I always ask, ask for them to show you the email has been removed from their account list on any/all devices. Know this is a lot, but hope this helps! Cheers!
If you have IOS and receive the apple ID and password and change all the information, all you have to do is log in with the apple ID in gamecenter and load up COC?
