I don't have a new AS, but on other trailers I've had over the years, there are typically two methods. Hopefully one of them will work for you.
Look for a opening in the track at the center of the window. It's normally just big enough to allow the thingys that run in the track to slip out.
Look for a small screw at the end of the track. The screw will keep the thingys from falling off the end of the track. Remove the screw, and then you can remove the curtains.
Hope this helps!
ps - I used the technical term "thingys" because I'm not sure if you have little plastic tabs that run in a track or something else.