How to wipe the OS from a BlackBerry device? - BlackBerryFAQ - Wipes data from the device (and third party apps in the newer OS)
Welcome to the forums.
BlackBerry FAQ - BlackBerryFAQ is a fantastic resource in addition to this site.
Also you can use JL commander (
How do I wipe the BlackBerry using Jl Cmder? - BlackBerryFAQ) to wipe everything from the device period.