Deauthorize Old Apple TV

Apple TV doesn’t have device “authorization” like computers have.

Your account will be on it, if you didn’t factory reset. Only the person that has the device can change that.

If you feel that your account credentials could be exposed, then you are advised to change the passwords for all services on it: Apple ID password and any other accounts.

if it was me then I would read

What to do before you sell or give away your Apple TV 4K or Apple TV HD - Apple Support

and consider changing my appleID password