How to Format Your Phone
Formatting a cell phone restores the device to the factory settings. The process will erase the memory on the phone, including contacts, pictures, and any other files. Formatting the cell phone is a necessary process before selling your cell phone or returning it to the store for an upgrade, because you can be sure your personal information is no longer on the device. You do not need any additional equipment to format your phone.
Select "Menu" and "Settings" from the phone's home screen.
Scroll through the Settings options and select "Security." On a Blackberry device, select "Menu," "Options," "Advanced Options," and then "Security."
Select "Restore to Factory Settings." On a Blackberry, select "Wipe Handheld."
Click "Yes" when the phone asks if you are sure you want to format the phone. If you have previously set up a password for your phone, you will enter it when prompted and click "Ok." Wait for the phone to restart.