what molding are you talking about? the one at the bottom of the window on the outside? if so its coated in plastic, if its smooth still just faded you can repaint them.
if they are cracked and pealing, you need to scrape/cut/sand it smooth, then paint and clear, wet sand, buff to a shine.
i did mine, and they were cracked and cutting people.
if you open the door, the latch side under the molding you'll see a screw, take it out, and then loosen or remove the side view mirror, then slide it back a inch or so and then lift it up and off.
if your a 4 door, the back door screw in in the front of the door, so open front door look for the screw by the molding. same deal lift up, pull back, then lift off, you'll feel it un hook.
mine came out like this, that white crap is compound.