Sorta long to type out, and I think if you're doing this type of stuff
you out to get an MB service manual, but basically (assuming you don't
have speakers in your doors) you under the chrome trim around the door
striker, the trim where the window meets the b-pillar, the trim behind
the door handle. Beneath the door handle trim is a screw, undo it. undo
the 2 screws in the horizontal part of the armrest, pop off that black
plastic trim around the door handle (first pop off the seat adjustment
buttons), no you have exposed a third armrest screw, pop that off too.
Pop off the cover for the light at the bottom of the door and
disconnect the ries. Now push upwards on the door panel to unhook it
and take it off.