Remove main user from Apple TV

is it possible to remove the former main account holder from an Apple TV?

my ex left his for my daughter, long story short I’d like to sign on without him knowing my passwords for everything (he’s very tech savvy and would be able to instantly if I signed in with my Apple ID and password which he no longer has) but I don’t know how to remove him from the device without involving our attornies.

He willingly left the Apple TV so my daughter would have television, so is there any chance there is a way I can sign him out and make myself the primary user?

thank you so much to anyone who can help!