Open the door and locate the screws on the backside of the hinge jamb, which is just inside the door panel's hinge. Loosen these screws with a screwdriver while holding the door, or have an assistant hold the door if possible. Remove both screws and set the door aside.
Find the screws holding the strike jamb to the wall jamb -- the part that mounts to the wall -- on the other side of the door. Loosen these screws with a screwdriver and remove the strike jamb.
Unscrew the two wall jambs from the wall with a screwdriver. The screws mounting the jambs to the walls are located inside the jambs, which are U-shaped steel channels. Pull the jambs off the wall after the screws are taken out.
Remove the drip tray and threshold by loosening the mounting screws with a screwdriver, then pulling them off by hand.