This worked on my pass through window. With the window closed, remove the bottom plastic piece where the window slides. Start at the end away from the slider. Once you get to the slider end, you should be albe to slide it out from under the window. You a screwdriver or heavy duty dental pick to get it started. Then repeat for the upper plastic piece. Once both are removed, you can then open the window and slide the slider all the way to the left. Finally pick it up, tilt out the bottom and then remove.
While you have it out, suggest you remove the bottom plastic piece from where the window sits when closed and clean the debris from under the track as this tends to build up and eventually clog the drain holes.
And make sure you make careful note of position, direction, and location of each plastic piece so you can reinstall properly of the drains may not work as intended.
2015 Ram 3500 4x4 Crew Cab SRW 6.4 Hemi LB 3.73 (12.4 hand calc avg mpg after 92,000 miles with camper)
2004 Lance 815 (prev: 2004 FW 35'; 1994 TT 30'; Tents)