To erase your Apple Watch without using your iPhone, follow the below process;
- On your Apple Watch, tap Settings > General > Reset > Erase All Content and Settings.
- Enter your password if prompted.
- For GPS + Cellular models, select whether you want to keep your cellular plan or remove it.
- If you plan to pair your Apple Watch and iPhone again, keep your plan.
- If you don’t want to pair your Apple Watch and iPhone again, select the option to remove your plan. If you aren’t going to pair with a different watch or iPhone, you might need to contact your carrier to cancel your cellular subscription.
- Tap Erase All to reset your Apple Watch to the factory settings.
