I just realized that Yosemite will over time, create multiple desktops, 1, 2, 3 etc which I can see via Mission Control. I'm not actively creating these spaces, but it is a pain to manually click and X out each window. I can't figure out why so many desktops are created, but I would also like a shortcut to close all of them at the same time. Any ideas or hints? I'm stumped!