You should be able to remove the rubber track the window slides. Look at the opposite side of the window where the window slides to, you should see the end of the rubber track. I use a small screwdriver to lift the rubber track out. Once you get it started just pull the track out. Once the track is out of the frame you should be able to lift the window and pull it toward you. That works for my Hehr windows.
Chuck & Teri, 1999 35 ft. Dolphin 5350, F53 Chassis with tag axle, Chassis build date 1/99 in Mexico, Banks System, Trans Command, Air Lift Air Bags on rear, Koni Shocks, Blue OX TruCenter, TigerTrak track bars front and rear, Roadmaster 1-3/4" rear auxiliary sway bar, 2013 VW Passat TDI SEL Premium, 1994 36 ft. Avion 5th Wheel. FMCA #F430129