How do I cancel the installation of the latest adobe flashplayer thing?

Okay so on Face book in order to do this “Pieces of Flair” you have to download the latest Adobe Flash player. Well, I clicked on the link ( http://get.adobe.com/flashplayer/) and I agreed and installed but then while it was installing it said “installation is corrupt!” and so I just canceled out of everything and thought I stopped the installation. Then this thing popped up that says “Installing Adobe Download Manager…” and it has a loading sign. It’s making my cursor blink and go crazy and it won’t let me close out of it. I tried restarting the computer several times and shutting it down, but every time i click on Fire Fox it pops up again and it won’t go away! How can I delete it? I just want to cancel the whole thing but I can’t figure out how to do it!