you will probably need a pair of removal tools (available from halfords). Basically they fit into the two sets of vertical aligned holes on the left and right side at the front of the stereo (there may be two plastic clips covering them depending on what tape deck it is) Slot the prongs of the tools in which will release the clips holding the stereo to the cage, give it a tug - an hey presto!
Don't forget to set the connections on the wiring loom of the jvc for a permenant live feed, or else it will lose its memory every time you turn it off