I do not have the phone or the password to unpair my watch and pair with different phone
Apple Watch Series 3, watchOS 7
Then you can't do that.
You need the credentials for the account the watch is locked to.
You can ask apple to remove the activation lock online on this page;
Online Activation Lock Removal Tool.
Or this;
If you can't remember/gain access to the apple id that paired the watch to the phone.Take the watch and it's receipt along with some photo id and any other proof of ownership to an Apple Store and request that they remove the Activation Lock for you.
How can I pair my watch with a different phone with no password
