its a rubber set window. meaning the rubber you see around the edge actually sandwiches between the metal and the glass.
as far as removal...this is how i have done a few times and this is NOT THE CORRECT WAY.(disclaimer)
i use a small (6in) pry bar and a long (12" or longer) thin flat blade screwdriver
I start in one corner and pry the edge of the rubber away and slide the screw driver past the rubber into the cab
then i place one hand on the inside and apply pressure to the glass while rolling the screwdriver along the seam
a little silicone spray helps out
BE ADVISED if you choose to do it this way, simply looking at the glass wrong with these tools in hand will shatter it.