Most Sears disposers are made by ISE which means they have a "twist mount flange" and you just rotate it counterclockwise to remove it. If it is one made by a different company then there are many possibilities as to how to remove it. If it was made by GE for example, (in which case it would be a true "Disposal"), then it has four spring latches and the easiest way to get it off is to break them. Others have large plastic nuts that screw
off or release a bayonet mount.