Cancel Downloads from the Mac App Store
If you ever need to cancel an active download from the Mac App Store, you can quickly do so in OS X (on any version) with a really simple trick.
There’s not much to the cancel download trick, here’s all you need to do:
Hold down the Option key from the “Purchases” menu in the Mac App Store, this causes the “Pause” button to turn into “Cancel”
If you click that “Cancel” button you will get a warning dialog box asking to confirm that is what you wanted to do, and reminding you that can re-download the app again for free at any time.
While clarifying the instructions on how to re-download Mac OS X Lion from the App Store I discovered this neat little trick; you can cancel downloads with a simple key modifier. The ability to re-download purchases from the Mac App Store is part of the personal use license for OS X Lion and other apps offered through the App Store as well, as long as you are downloading them on your personally authorized Macs using the same Apple ID. This means you can cancel downloads at any time, resume them if need be, or start them again on your other authorized Macs with the same Apple ID.
This works to stop or cancel downloads in all versions of OS X, including OS X Yosemite, Mavericks, Mountain Lion, and whatever else has the App Store.