My black Apple TV box keeps asking me for my password for an email address that I haven't used for several years. How can I get the Apple TV box to allow me to put a new email address & password in so that I can activate the Apple TV acct?

What is your model Apple TV? Identify your Apple TV model - Apple Support

• If you want your old Apple ID account to associate with a different (unused as far as Apple is concerned) email address: Change your Apple ID - Apple Support
• If you want to use your Apple TV box with a different Apple ID account: Reset or restore your Apple TV to its factory settings - Apple Support. Then set it up “as new” with the wanted account.
• If you have an Apple TV box (4th generation or later) with a working account, but you get asked for an old account, then that indicates that one of the apps wants to update, but it was installed with the other old account. Delete and reinstall that app to solve it. If unsure which app, then delete multiple apps, or reset to factory settings.