What to do if you forgot your Activation lock I’d and password
How to reset Activation Lock
Apple Watch Series 6, watchOS 7
Question marked as
Go to https://iforgot.apple.com to retrieve the ID and reset the password. See also If you forgot your Apple ID - Apple Support
Failing that, as long as you are the original owner and can produce a proof of purchase (which must include the serial, IMEI or MEID number) you can request unlocking as detailed here: Activation Lock - Support. Note that the process will completely erase the device.