As far as I know, if you ARE the current guild leader, the answer would be /yes. Give them the heads up, if you haven't and move out. If they are a "don't really care" type then promote and high tail it outta dodge!
Yes, bring up the guild window by hitting your g key. Then find your name, there is a little head icon to left of your name. I am not sure if your left or right click that but once you do it the right way and drop menu comes up and there you choose "leave the guild".
