I had the same Windows API (application programming interface?) error as above. I dragged the entire MiKTeX 2.9 folder to the trash and then went to the "Change or remove a program" option from Control Panel. MiKTeX 2.9 was still on the list, but when I clicked "Uninstall", I got a message saying that it may already be uninstalled and asked whether I'd like to remove it from the list of Programs - I clicked "Yes".
It seems to be gone!