To unlock this Apple Watch, enter the Apple Account and password that were used during set-up.
To unlock this Apple Watch, enter the Apple Account and password that were used during set-up. Forgot that password
Apple Watch Series 8, watchOS 10
Question marked as
If you have forgotten the Apple Account password, have a look at how to reset it:
If you forgot your Apple Account password - Apple Support
In case this does not work, and you have proof of purchase documentation, you can start an Activation Lock support request for your watch.