 To really erase your phone, you've got to do a factory reset and follow it up with a more thorough data erase. This involves using specialized software such as iShredder or Secure Eraser. It overwrites the entire phone storage with random data multiple times. This process makes it almost impossible for anyone to retrieve your personal data. Again, the steps are 1. Factory Reset and then use iShredder or Secure Eraser. Enter to win a $1,000 vacation gift card at winfromkim.com.