Instructions
Turn on your Xbox 360 console and open up the "My Xbox" menu.
Scroll all the way to the right and select "System Settings," then choose "Memory."
Select your storage device (usually "Hard Drive" or "Memory Unit"), and then press "Games."
Navigate to the game you wish to undo the installation of an update for, and then select "Game Options."
Choose "Delete" from the list of options. Your Xbox game update along with the game will now be removed completely from your system. To reinstall the game, insert the game disc into the console, select "Game Details," and then choose "Install."