Erasing everything off your iPhone 4, 3GS, or 3G is a very common thing to do if you are planning on selling your iPhone, giving it away, or even having it repaired. This allows you to know that all your personal data cannot be read by anyone that has access to the iPhone. Make sure before you start to sync your iPhone with iTunes so that if needed it can be restored at a later date.
IMPORTANT: If you are using a jailbroken iPhone you will first need to remove the jailbreak before the data can be erased. Doing these steps well your iPhone is jailbroken will result in your iPhone not being able to boot.
- Go into Settings and select General.
- At the bottom of the screen select Reset.
- Now select Erase all Content and Settings from the list.
- When warnings appear that your data will be erased just select Erase iPhone.
- You iPhone will now start the erasing process. This may take some time to complete.