HOWTO: Wipe Handheld – erase data on a Blackberry

To reset your BlackBerry (erase all personal data, reset to factory defaults)

From the home screen, select Options | Security Options
Select General Settings
On some devices, you now select “Services”. If this isn’t available, go to next step.
Click the trackwheel, and select Wipe Handheld
Click Continue
When prompted, type “blackberry” to continue
Your BlackBerry device will erase all the data and put the settings back to factory default