Along the bottom edge of the rubber there is a metal clip. Remove that clip with a screwdriver.
You should see the ends of a rubber 'rope', pry one end out and pull it out all the way around the glass. You should be able to pry the window out of the rubber pretty easily now. I had no trouble taking my sliding windows out a few years back. Took about 10 minutes total once the rubbers were out.
Rene