Are you the original owner of this watch or did you buy it used? If you are the original owner, these links will help you:
If you forgot your Apple ID password - Apple Support
How to pair your Apple Watch with a new iPhone - Apple Support
If you bought a used watch and can't get help from the seller, these links will be valuable information:
How to remove Activation Lock - Apple Support
https://discussions.apple.com/docs/DOC-250001038