Cannot log into App Store via Apple TV

My exroommate and I split and Apple TV second generation. He moved out over a year ago.

I am unable to access the App Store from inside Apple TV, because it is set to his account - even though I am logged into Apple TV as my own account.

There is no way available to me to log him out of the App Store so I can log in and get new apps, etc.

Other than resetting to factory default, is there anyway I can get to the App Store to install new apps or update broken ones? (for example, YouTube does not allow me to scroll left or right, only up and down. No other app does that. Twitter has no way for me to log in, I am stuck in their generic pop culture feeds.)

Thanks!