Things You'll Need
Instructions
Connect the flash drive to one of the USB ports on the front of the Xbox 360.
Move to "My Xbox" and select "System Settings."
Select "Memory," then "USB Storage Device."
Press "Configure Now" to delete everything currently on the drive and format the drive for the system.
Select "Customize" to select how much memory you want to format. Move the slider bar to the desired amount you want to format. Click "Configure" when finished.