Ron's advice and picture are correct. A brief word of warning: If you haven't done so, disconnect the battery cable before you do this. Since you have to have the ignition on to remove the switch, you run a risk of burning out your points by the time you find the little button, get it depressed, remove the switch, swap it out, etc.

When I changed my ignition switch I thought it would take a few seconds and didn't think to disconnect the power. I quickly realized that until I coiuld find that little hidden button by feel, that I was screwing around for several minutes with the ignition on.

Since you're removing your entire dash, you've almost certainly disconnected power. Others reading this might not have, hence my advice, for what it's worth.