The Apple iPhone 4 has anti-theft and may affect how you are able to master reset the device.
- On your device’s Home screen, tap Settings.
- Tap iCloud.
- If you’re asked to sign in, enter your Apple ID, or if you don’t have one, tap Get a Free Apple ID then follow the instructions that appear.
- Tap to turn on or turn off Find My iPhone.
- If turning on, tap Allow.
- If turning off, enter your Apple ID password and tap Turn Off.