Can't log in with my Apple ID

Hi, so I have this Apple TV which use to be my uncle's. He will no longer return so I kept it, but now I can't seem to be able to log in which my Apple ID. Firstly, I can't seem to be able to find where to get rid of his account. Anyway, I tried logging in with iCloud and iTunes with my own account. I am 100% sure my email and password are fine, but I receive 3 more verification codes once I send the one I had already received, therefore I can't log in although I've received an email stating I've already logged in. Does anyone know how to fix this?