It's a drastic step, of course, because when you get rid of all the music, apps, email, and settings from your phone – unless you backed it up, that is you won't get it back. Still, in situations like those described above, it can be necessary. For now, you may try to use Phone Transfer for iPhone.
Phone Transfer can delete your iPhone's setting and erase all the data on your device and turn off iCloud, iMessage, FaceTime, Game Center services. So you need to make sure that everything on your iPhone is backed and the data left on your phone is useless or worthless. When everything is set, click and download this app below.
Phone Transfer provides a secure way to erase your data from your iPhone so that no one can get the information from your iPhone/iPad/iPod.
Step 1 Connect your iPhone or iOS device to computer
Download the Phone Transfer above and install it on your computer (function is only available on Win version). Click the Erase Your Old Phone section. Connect your iPhone to the computer. This tool will detect your iPhone model automatically.
Step 2 Delete everything from iPhone
Click the Erase Now button. A dialog window will pop up. Read the tips and enter “delete” in the box. Then, click Start to Erase to erase all of your data on your old iPhone/iPad/iPod.
For now, you can sell your iPhone or give it away without worrying that your information would get sold by some harbor evil designs. Click and download it below.