Can't uninstall a file

I downloaded a voice changer, thinking it would be funny to trick my friends. I realized it was a piece of crap, so I uninstalled it with no problem. But I had also installed 3 voice packs for it. 2 voice packs I uninstalled like normal, but the third one wouldn't let me. When I went to uninstall it, a window popped up:

http://imm.io/VSvT

Then I clicked on OK, but then this window popped up:

http://imm.io/VSw4

So after that I just pressed OK then Cancel and then this popped up after the 2 windows were closed:

http://imm.io/VSwr

Someone please help with this. I've tried to reinstall it but it goes through the same process as when I try to uninstall it. If you need more information just ask me.