on each side of the radion there is a cover you need to remove those and insert a FIRM wire through the holes that you see on each side. insert the wire that is u shaped through top and bottom, there are clips on the side of the radio that eed t be pressed inward so you add pressure to the wire outward and pull as you are pressing, this should release the clips. if you don't care for the radio, you can force pry it out cause those lips can be a pain in the butt.
New Method! If you take four 1 1/4" drywall screws and screw them halfway in to the four little holes, pull to the sides and slide out your radio! they are easily sturdy enough to push in the clips and make a great handle to pull the radio out with!