There should be either 2 or 4 little holes at the corners of the stereo.. bend a coat hanger or similiar device - push it into the holes at the same time. You'll hear a click ( a bit finiky so move it around slightly until you hear the click ). Basically the stereo is held in place by 2 clips that are released when you push the in allowing the stereo to release. In some cases it can take 2 mins in others it can drive ya mad and take over an hr!
No need for force or pressure and most definitley do not remove any part of the dash..