Normally to remove the door you remove the inner rubber stops, they are big black square rubber things.
Then you see at the back on the bottom is the door stay (crap on the mk7) held on by 1 or 2 8 or 10mm bolts, remove them and it, then at the back of the middle rail is a plastic cap, remove that.
If i remember correctly that is it, open the door and with a friend open the door all of the way and it'll come off completely with a bit of jiggling.
Reverse should see it refitted.
However, they aren't that easy to half remove without damaging the rails or rollers, if you've pulled a roller out of the upper rail them you need to see if you've damaged it, if so then you may have to either try and bend it back or worse case, remove the door completely and see if you can straighten the rails and roller brackets etc.
If there is no obvious fix to you then i think it best to take it to someone who's in the trade
Ps the door can be heavy and awkward to try and do on your own