you can buy a kit to do it but it doesn't work that well and it costs $15 bucks. Use thin pick tools or allen wrenches. Basicly the cage clams to the radio a few inches down those holes. You can insert two thin pieces of metal push outward and pull it out. You have to pull hard becuase their is a bobber piece stuffed into a stock metal retaining piece of the dash.
PS doen't try to get it from behind you'll just cut the hell out of your hands.