I understand that you're locked out of your Apple Watch due to a passcode, and I'm happy to help. Since the device is not paired, you can follow these instructions:
If you forgot your Apple Watch passcode
Use your Apple Watch
If you don't have your paired iPhone, you can still remove the passcode from your Apple Watch.
- Keep your watch on its charger until you complete these steps.
- Press and hold the side button until you see Power Off.
- Firmly press the Power Off slider, then lift your finger.
- Tap Erase all content and settings.
- Wait for the process to finish, then set up your Apple Watch again. When asked, restore from a backup.