If you have UnleashX, go to File Explorer, and navigate to your Apps/XBMC folder. On the other side navigate to your Dashboard folder. Delete all cotents inside the Dashboard folder. Once that is done. Select All the files/folders inside your XBMC folder, and copy them, or move them. Just make sure you have a back up of your Xbox before you do this, so you can reverse it, if anything happens. If you follow this exactly, you should be good to go. This way, you don't have the old XBMC cluttering up space if you don't use it anymore.