Turn your iPhone on. Hold down the “Power” button at the top right corner of the iPhone until the Apple logo appears.
Tap the “Settings” button on the “Home” screen of your iPhone. This is a gray icon with an image of gears on it.
Tap the “General” tab. This opens the general settings of your iPhone.
Scroll to the bottom of the “General” settings window and tap “Reset.
Tap “Erase all content and settings.” A warning will pop up indicating that all media, data and settings will be erased and reset. Tap “Erase iPhone” to format the entire iPhone.
Tips & Warnings
Fully charge your phone before formatting your iPhone; the process could take a long time depending on how much data you have stored on your phone
Formatting your iPhone will erase all data and restore it to the original factory settings.