I have an old iPhone 5 and bought a new iPhone 7 Plus last week. I am going to sell the old iPhone and want to remove all sensitive data on it. My question is a simple factory reset enough to permanently destroy the data?
If this issue is only existent with iTunes, head over to Download iOS Firmware for iPhone, iPad, iPod Touch, Apple Watch and Apple TV. and download the latest IPSW for your device (or any IPSW that is currently being signed (shows up in green text not red)), then when you come to restore using iTunes, hold the shift button (windows) or command button (Mac OS) and then press the restore button, a new window will open, direct it to the .ipsw you downloaded earlier and it will verify and use that .ipsw instead.