If you have only one Apple ID and it does not show your Apple Watch then it might be successfully removed from Activation Lock, but not yet fully erased in the watch itself. If your watch will cooperate, try this.
Press and hold the Digital Crown and the Side Button (together) about 10-15 seconds until the white Apple logo appears. This will completely reboot the watch and avoids conflicts in memory.
When the watch has restarted, try to follow the Lost Passcode process to erase the watch
If you forgot your Apple Watch passcode - Apple Support
If that doesn't help, please post back to tell us the exact words on your watch screen and/or on your iPhone. Don't try to interpret to say "it is locked" - just tell us what you see with your eyes. (If it is not in English, please add as close a translation as you can manage). If it is easier, get a photo!