Watch

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.

You have to unpair the watch from the old phone first,a watch can only be paired to 1 phone at a time.

Erasing a watch doesn't remove the activation lock;