Instructions
Power on your XBox 360 and flip through the menu screens using the directional until you find the "My XBox" menu set. Scroll all the way to the right until you reach the "System Settings" menu and press the "A" button.
Scroll through the options in the System Settings menu until you find "Memory" and press "A."
Highlight the storage device you want to perform maintenance on and press the "Y" button. Scroll down to the "Clear System Cache" button. You will see a message that asks, "This will perform maintenance on your XBox 360 storage device. Do you want to continue?" Highlight "Yes" and press "A."