There is a method you can use to remove the IT policy using the official RIM loader.exe application. This is a much cleaner method & leaves NO trace of ANY IT POLICY.
You need to ensure you have Blackberry Desktop Manager installed & also have the latest device software installed for your device.
Desktop software and device software are available here: http://na.blackberry.com/eng/support/downloads/download_sites.jsp
You will need to select your carrier from the list in your region.
PLEASE NOTE THAT THIS METHOD WILL WIPE YOUR DEVICE TO A FACTORY STATE, REMOVING ALL PERSONAL DATA & REMOVE THE IT POLICY.
If there is anything important on your device, please back up using the "ADVANCED" function on Backup/Restore in desktop manager.
I suggest you backup only what you need, ie SMS, Contacts etc. Please note that you can actually backup the IT policy, so if you do this, when you restore the backup to your device, the IT policy you had just removed will be restored on the device (FAIL!)
If you are unsure how to backup your device via the advanced method, please PM me and I can walk you through.
Please ensure that your device is plugged into your PC via USB if you chose to skip the backup, if you hadnty plugged it in already.
After you have done the backup, you will need to open a command prompt on your PC, by going to Start -> Run, typing in cmd and pressing enter.
In the command prompt, you will need to locate the Apploader folder, provided you have a C drive, it will be located at:
C:\program files\common files\research in motion\apploader
(the command you would use is cd \program files\common files\research in motion\apploader)
You will then type in (without the quotes) "loader.exe /resettofactory"
The device will then proceed to wipe itself and then restart.
All that is left after your device has started back up is to restore your personal data