How do I unpair an Apple Watch from a previous iPhone?
I have the watch it was connected to my old phone, but I have a new Emil address and the watch won’t unpair
[Re-Titled by Moderator]
iPhone 14, iOS 18
Without knowing the Apple Account and the password that has been used to set up the watch, you can not pair it to another iPhone:
Unpair and erase your Apple Watch - Apple Support
However, if you have proof of purchase or ownership, as explained in this related article, the official Apple Support can disable the Activation Lock:
Additional Support - Activation Lock