Instructions
Push the following button sequence using your Xbox 360 controller while in the "Dashboard": X, X, left bumper, right bumper, X and X. This will cause a system maintenance prompt to issue on your screen.
Choose the "Yes" option when the system maintenance prompt asks if you wish to continue.
Push the "B" button to move back into the main menu of the "Dashboard" once the system notifies you that your cache is clear. All game updates are now cleared from your hard drive.