Power off your iPad or iPhone – press and hold the power button, then slide the slider on screen to turn it off completely.
Next, open up iTunes on your PC or Mac. Make sure it’s the latest version.
Press and hold the Home button.
Plug your iPad or iPhone into a USB port on your PC or Mac using the iPad lightning cable.
Release the Home button when you see the recovery screen (shown above).
You can now restore your iPad to it’s factory defaults from the iPad page in iTunes.