Follow these steps
On your iPhone, iPad, or iPod touch, go to Settings > General > Reset. Then tap Erase All Content and Settings.
On your Apple Watch, go to Settings > General > Reset. Then tap Erase All Content and Settings.
- Before you erase your iPhone, iPad, or iPod touch with iOS 10, make sure that you sign out of iCloud. Otherwise, your device might remain in Activation Lock. Learn what to do if you erased your device and need to turn off Activation Lock on your iOS device.
- In iOS 10.3 or later, go to Settings > [your name] > Sign Out.
- In iOS 10.2 or earlier, go to Settings > iCloud > Sign Out.
- Erasing the content and settings on your Apple Watch doesn't remove Activation Lock. You need to unpair it from your iPhone or delete it from Find My iPhone. Learn how to turn off Activation Lock on your Apple Watch.
- If you don’t remember your Restrictions passcode or can’t access the Restrictions settings for your iPhone, iPad, or iPod touch, use iTunes to restore your device to factory settings.