It is what they call an encapsulated unit and it has to be cut out, usually from the inside with what is called a Fein Knife. You need to remove the interior trim, revealing the urethane seal between the edge of the slider and the cab. The Fein knife has a blade on it the oscillates back and forth and can be inserted into the urethane seal against the Vein so you don't cut into the frame of the slider. Holding pressure toward the inside of the cab right against the pinchweld with the blade will keep you away from the slider frame. As you work your way around the pinchweld cutting the urethane seal you can have a friend apply very light outward pressure to the slider which makes the urethane easier to cut. You also have to make sure you don't push the blade in too deep or it will slide past the shoulder on the pinchweld and take the paint off the lip all the way around the slider on the outside of the cab. It can be a pretty difficult job sometimes, it just depends on how much urethane Dodge used to install it and if it has ever been changed before. Good Luck!
You referring to the slider enter window section itself?
if so I've done that, can't remember exactly how, it involved pulling out plastic channels top and bottom that the sliding center section actually slides on then removing that glass section.