Blackberry 9900 Autoloader [better] -

The Autoloader performs a "Clean Install." It does not preserve user data. For enthusiasts restoring a used device, this is the perfect way to ensure the phone is wiped to a factory state, free of previous user data, corrupted files, or lingering viruses.

Once the command prompt says "Operation Complete" or "Rebooting Device." blackberry 9900 autoloader

Using an Autoloader is straightforward but requires precision. The Autoloader performs a "Clean Install

However, if you are looking for the raw OS file to force an install: free of previous user data