Right below the volume knob and the DX/Man button. Get an old credit card, cut it in to strips that are slightly smaller and insert them pointing towards the outside of the radio rather than straight in or pointing toward the middle of the radio. Once they're all the way in, the bits that are sticking out should be pointing inward (ie toward each other, rather than away). "Open" them up and it should release the clips inside. I stick my finger in the cassette slot and tug from there.
Hope that helps