I used to have DIVX on my computer, but I uninstalled it when an update changed it beyond recognition. However, I do not remember it being difficult to uninstall.
If you go to 'Control panel' - 'Programs and features', does it show up in the list of installed programs ? If it doesn't, then it may be that all you are left with are the desktop icons, and these are easy to remove. Right click on the icon, and then click on 'Delete' in the drop-down menu that appears. You may then get a confirmation pop-up telling you this only removes the icon, not the program, but that is what you want to do. One icon, gone.