How to erase passcode from apple watch

Open the Settings app on your Apple Watch.

Tap Passcode, then tap Turn Passcode Off.

Or;

1. Put your watch on its charger and keep it there until you complete these steps.
2. Press and hold the side button until you see Power Off.
3. Press and hold the Digital Crown until you see Erase all content and settings.
4. Tap Reset, then tap Reset again to confirm.
5. Wait for the process to finish, then set up your Apple Watch again. When asked, restore from a backup.