How do you create a new Apple ID for your apple watch
How do you create a new Apple ID for your watch if you forgot your old Apple ID information?
Apple Watch
Your Apple Watch uses the ID used on the phone it is paired to. Have you checked Settings on the phone to see if you can find the ID you forgot?
See if you can recover the ID/password. Use every email address you can think of.
Apple ID - How to find your Apple An iCloud e-mail address is an Apple ID.
If you forgot the Apple ID password, enter the Apple (iCloud) ID, and click Forgot Password. See if you can get a Rescue or Notification email option if necessary. Link to contact Apple Support at the end of the 2nd article.