I can’t use my Apple Watch because I locked it on an old phone
It’s locked to my old phone
Question marked as
Google can be your friend…
To unpair and erase watch and remove Activation Lock
From a web browser,sign in to iCloud.com with your Apple ID.
Go to Find iPhone.
Click All Devices at the top of the screen.
Click your Apple Watch.
Click Erase [device]. Select Next until the device is erased.
Click Remove from Account.
Now you can setup your Apple Watch.