How do I pair my watch with my phone if I can’t remember my old email or password
How to pair my watch with my phone when I can’t remember what email adress and pass code I used
Apple Watch
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 (iCloud) 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.