If you have a tilt column unscrew the tilt lever and then remove the upper and lower covers around the top of the column.
Remove 3 tamperproof torx screws and remove ignition switch from column.
With key inserted and switch in the LOCK posiiton, depress lock cylinder retaining pin with a small screwdriver. Rotate cylinder to the OFF position and this will unseat the cylinder from the switch. Rotate back to LOCK position and remove key, then separate cylinder from switch.