Is the trim peace you want to replace the black moulding that runs along the back of the door frame ?
If so then this is haw its done
1 remove the moulding that runs along the top of the door . Do this by using a plactic pry bar and leaver it up at the end of the door , its clipped to the door there , then its held to the window seal and door by 4 clips . The window seal might come off with this moulding . Be careful not to mark the paint as this moulding can be tight.
2 pull back the outtor door seal and look for the 2 small screws that hold the damaged moulding on , they are tx 15 screw heads , take them out
3 open the window and twist the moulding off the door and slide if foward off the door .

 

Thank you!

That's what I thought, but I wasn't sure how to get the trim along the top of the door/ bottom of window off. Hopefully, I won't botch it too bad.

 

I know it?s an old post but just curious how it worked. I have to do the same repair this weekend