Magic Lantern is an enhancement atop of Canon's firmware that frees your Canon DSLR, allowing you to use many useful features. Initially developed for filmmakers, it now has functionality for both photo and video enthusiasts, including manual audio, zebras, focus assist tools, bracketing, motion detection and much more. It is an open (GPL) framework for developing extensions to the official software. It does not replace the existing firmware, but instead runs along side of it. There is no need to "uninstall" it -- simply format your card to reboot to the stock Canon firmware.