Is there any way you can force it all the way down? esp if youre replacing the regulator. When i replaced both my rear ones you needed to push the window allll the way down, then pull off a little plastic clip retainer that stops the window from sliding off the rail (one of my windows didnt have this clip. Then once at the very bottom, you can angle the window out of the rail - i dont know if you can remove the window off the regulator unless the window is at the bottom.
Hope this helps!
Hope this helps!