Assuming that it is aluminum track, which does not go around corners, you have four individual pieces. Look in the corners between the pieces of track, and see if you can find a gap in the piping, or welting, between two of the tracks. Spray all the way around with soapy water, and see if you can slide the whole thing around to where that gap with no piping will come out of the track, and from there, you just work it all the way around. The piping may be in more than one piece, therefore more than one gap to work with.
It would be much easier to just drill out the rivets on the most accessible piece of track, and start from there, although it would help if the gap in the piping was at one end of the track you remove. If that doesn’t work, remove the next section of track.
Of course, if you are replacing it, the easiest thing to do is cut it down. If you’re trying to repair the zipper, then you have to go the more complicated route.
If you’re just trying to save it for a pattern, cut the piping in each corner, pull the four pieces out, and the bag will drop out of the track.
No matter what method you used to remove, the new/repaired one has to be reinstalled somehow.
What is the end game: remove, repair, replace?
edit: I make my own welting, with cording or small PVC tubing, so it just occurred to me that some of the things I said will not apply if it is something like Keder welt, shown in the link below. If that’s what you have other methods apply.
Keder Awning Rope attaches to the edge of fabric and slides into awning track for a strong, nearly waterproof attachment to a hard surface.
www.sailrite.com
