Below are the steps to completely wipe out your Samsung Intrepid (SPH-i350) and reset the phone to its factory defaults. Note: This process WILL delete all your contacts and any files you have saved to the phones internal memory. So complete a FULL sync of your phones data or make sure to backup everything manually.
1) Push and hold the power button until the 'Shutdown' box appears
2) Touch 'OK' to power down the handset
3) Press and hold the 'Enter/Settings' key (silver rectangular button in the middle of the directional pad) and the power button to restart the handset. (Do NOT let go of either key until the format screen appears)
4) Touch the green Talk key to begin formatting the handset (Again, this will delete all data and restore the factory default settings)
That is all!