Instructions
Connect your Xbox 360 to Xbox Live. Press the Xbox Guide button on the controller, highlight "Connect to Xbox Live" and press the "A" button if your console is not already connected. If necessary, the console will walk you through the free Xbox Live account creation process, which involves entering your email information and choosing a valid gamertag name.
Highlight your profile from the "My Xbox" section of the console menu and press the "A" button.
Highlight "Profile" from the available options and press "A." Press "A" to select "View Games" from the profile screen.
Highlight the game you wish to remove from your game history and press the "X" button. Press "A" to confirm that you wish to delete the game from your history and the title will be deleted.