This will only work for New USB flash devices that are plugged into the machine. To fully disable the USB Storage driver, you'll need to do the following:
Open Registry Editor.
In Registry Editor, navigate to the following registry key:
Locate the following value (DWORD):
and give it a value of 4.
Close Registry Editor. You do not need to reboot the computer for changes to apply.
To re-enable the setting, go to the Reg Key above and give the Start Dword a value of 3