How do I remove the chuck if I need to use different accessories?

Lock the switch trigger in center position, insert a 5/16 inch or larger hex key into the chuck and tighten it securely, then tap the hex key clockwise with a mallet to loosen the chuck screw. Next, tap the hex key counterclockwise to loosen the chuck from the spindle, then unscrew the chuck by hand. Note that the chuck screw has left-hand threads. (Page 14)