I bought Apple Watch for my self and I forgot my password for my iCloud and I want to use the watch again with my new iPhone and the watch is locked to my other iPhone that I no longer have what do I do

If you forgot your Apple ID password

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.

Then;

Setup your Watch to a new iPhone