1. Disconnect the (-)Negative battery cable.
2. Remove the Radio's Fascia Panel. (Pull the panel) The radio will be attached to the reverse side of the Fascia with 4 screws.
3. Remove the mounting screws.
4. Disconnect the Antenna and Electrical Harness.
I am assuming that you are installing a new / replacement head unit. I suggest that you purchase a wire harness / dongle that will allow you to "plug and play" so that there is no cutting of wires. Definitely makes the task much easier and if (for some reason) you feel like re-installing the original head unit it is as easy as removing the harness and plugging the old unit up. You should be able to find one of these at your local auto parts dealer. here's one from ebay :
http://cgi.ebay.com/1990-1994-Hyundai-Exce...0925142004r2749Looks like that one is going for a buck.