Lost Apple Account information for Apple Watch

these are the steps that you need to do

What to do before you sell, give away, or trade in your Apple Watch, or buy one from someone else - Apple Support

otherwise you will not be able to use the watch

activation lock is not a thing on the ipad it's a theft protection on apples servers

it needs to be removed

About Activation Lock on your Apple Watch - Apple Support

if you don't know your appleID password If

you have forgotten your Apple ID password – Apple Support (UK)

then you will need the assistance of apple Activation Lock - Support (apple.com)

and or

 Apple Support

And or

 Contact - Official Apple Support

and or

Genius Bar Reservation and Apple Support Options - Apple

If you forgot your Apple Watch passcode - Apple Support

If you require further assistance beyond this quick reply; for a more tailored assist, recommend that you open your own thread.

I haven’t worn my apple watch for a while forgot my 4 digit passcode how do I reset it

try

If you forget your Apple Watch passcode – Apple Support (UK)