Step 1: On your BlackBerry Home Screen click the "Options" choice.
Step 2: Next you'll need to click on the "Security Options" followed by "General Settings" If you're using a version of BlackBerry software lower than 4.1 you can simply click "Security" and avoid the Security Options choice altogether without having to update the system.
Step 3: Open the General Settings Menu and click on "Wipe Handheld" next click "Continue".
Step 4: When prompted for a word type "blackberry" and hit the Enter key.
It's really that simple, you've now deleted the data from your BlackBerry cell phone.