I can’t remember my old Apple ID or password to unlock my watch

Check your web browser autofill entries, the Keychain, and other records, or use Apple's iForgot service, or contact their Account Security team, or if you're the unit's original owner and have encountered the activation lock, click here and submit an unlock request.

(241091)

If your Apple Watch is still paired to your I\Phone there is a very good chance you can reset your Apple ID password using the iPhone. At that stage you know all the answers. See the advice in this help document,

If you forgot your Apple ID password - Apple Support