Pateco, It is pretty simple. The frames will push out from the inside. What is on the inside is just a trim piece. Once you get the frame out you can push the plexiglass out just by trimming/slicing the adhesive around the plexiglass. Mine was covered with silicone which is hard to get out of the cracks once the glass is clear of the frame. I bought some silicone remover from Home Depot and got after all the left over silicone sealant with that, some rags and a wire brush. You have to get it completely clean to get a good seal. I also used some 400, 600, 1000 to clean up the frames and finished with a coat of polish. We replaced ours because they were pretty crazed, we used a similar tinted Lexan which is much stronger than acrylic, our glass guy just cut them from the old acrylic. I laid a good bead of Boat Life Life seal (black because the windows were dark gray) on the inside of the frame, where the Lexan lies on the frame and fit it in, pushed it in place, gave it a good push and set some heavy items along the frame and let it dry. Then glazed the space between the edge of the Lexan and the frame at an angle. I used butyl tape around the outside frame, and in the screw holes as well one year and no leaks. Be careful if you use the black because it can be hard to see if you missed any spots as you are glazing the frame edge. Also check the plywood filler between the two fiberglass pieces for rot and fix that before reinstalling. Also we just used some heavy plastic tarp cut wider than the window frame and duct taped it on the outside. Did fine for the week it was covered. Here are some pics of the process. Just realized don't have any of the finished product in the boat. But you can see the result in the two finished ones.