Erase Apple Watch
In some cases, you may need to erase your Apple Watch—if you forgot your passcode, for example.
Erase Apple Watch and settings
Open the Settings app on your Apple Watch.
Go to General > Reset, then tap Erase All Content and Settings.
If you have an Apple Watch with a cellular plan, you’re offered two options—Erase All and Erase All & Keep Plan. To completely erase your Apple Watch, choose Erase All. If you want to erase and then restore it with your cellular plan in place, choose Erase All & Keep Plan.
You can also open the Apple Watch app on your iPhone, tap My Watch, go to General > Reset, then tap Erase Apple Watch Content and Settings.
If you can’t access the Settings app on your Apple Watch because you’ve forgotten your passcode, put your Apple Watch on its charger, then 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.
After the reset finishes and your Apple Watch restarts, you need to pair your Apple Watch with your iPhone again—open the Apple Watch app on your iPhone, then follow the instructions shown on your iPhone and Apple Watch.
Remove your cellular plan—Apple Watch Series 4 (GPS + Cellular) and Apple Watch Series 3 (GPS + Cellular) only
If you have an Apple Watch with a cellular plan, you can remove it at any time.
Open the Apple Watch app on your iPhone.
Tap My Watch, tap Cellular, then tap next to your cellular plan.
Tap Remove [name of carrier] Plan, then confirm your choice.
You may need to contact your carrier to remove this Apple Watch from your cellular plan.