To deactivate your Xbox from your account, please visit www.cinemanow.com/mydevices. This will bring you to your device manager for your CinemaNow account. Find the name you assigned the Xbox and click on 'DEACTIVATE' next to it. You will also need to deactivate the device named [Your Xbox Live Profile name]-Roaming. This is linked to your Xbox Live profile for uses when you sign into another Xbox.