Factory Reset of iPhone 4, iPhone 5, iPhone 6
1. Go into ‘Settings’ and select the ‘General’ tab
2. Next, you’ll see many options, but what we’re looking for here is to ‘Erase All Content and Settings’
3. Tap on it and confirm your intentions to wipe all iPhone data clean.
4. Your iPhone will start doing its magic and in a few minutes it will reboot completely clean and fresh, as if it was just out of the factory floor.
Note that this tutorial will work with the latest versions of iOS with phones like the iPhone6, 6 Plus, iPhone 5s, iPhone 5c, iPhone 5, iPhone 4s, etc.