First step is to disengage the brakes. Then, the easiest way to take the rear wheel off (imo) is to flip the bike upside down, pull back the QR lever, then slide the rear wheel up and out. The chain will catch on one of the sprockets of the wheel but just lift the chain up and off of it and you will be good. Here's a better video detailing what I just said:

http://www.youtube.com/watch?v=cvu6F...2D4EB862ECE34F