I'm trying to remove a deadbolt. A dozen websites advise to remove the screws on the inside of the door. Mine has no visible screws. Some say if there are no visible screws, remove the cover plate with a flat screwdriver. Mine does not come off with a flat screwdriver. Where one would hope to see screws, mine has irremovable rivets. The deadbolt is of the type with a keyhole on both sides of the door, and the apparatus appears symmetrical.