I need to do some rust repair on my back door and need to remove the plastic cover on the bottom of the door. How is this plastic fixed to the door? Any tips on how to remove?

I'm not certain on this exact strip on this exact chassis but I recall it is something like; on the inside edge of the door either at the front edge or the rear edge or both, there is a stainless Philips head screw you remove that and slide the strip either rearwards or forwards.

Sorry that's 124 info!

126 you remove the screw located behind the weather strip on the rear edge of the door at the height of the trim panel's top edge. Then you use a tapered plastic wedge or similar tool starting on the top edge at the rear working along that edge forward popping the plastic "buttons" straight out
BUT NOT the last connection at that trim panel's top forward most corner. Then starting at the forward end of the bottom edge pop the "buttons" straight out working your way rearward BUT Not the last connection! Slide the panel forward and pull gently outward to disengage the lower last connection "ear" freeing the entire bottom edge of the panel, then slide the whole rearward and gently outward to free the upper last connection "ear" thereby completely freeing the panel. The "ears" are hook shaped that's why you can't pull them straight outward to free things without damaging them.

If you have a plastic wedge tool this is really quite easy as you get the tip started and then just firmly push the tool further and the wedge shape pops the plastic male studs out of the female plastic receptacles.

Great info. Thanks so much. I have the plastic wedge. Should be easy if you know the trick.