You could try to emulate Rene Larsen's solution from a previous question on the Apple Stack Exchange site:
I've just installed and then uninstalled iconStiX again - just to see where the stuff was placed.
The uninstall is like this (see Readme.pdf in iconStiX.dmg):
Throw away the following 4 items into the Trash:
- the iconStiX program in your Applications folder (or any other place of your choice)
In your ~/Library/Preferences:
- li.loos.trollin.iconStiX.plist
- li.loos.trollin.iconStiX.LSSharedFileList.plist (if any)
- a folder named iconStiX in your ~/Library/Application Support folder
Empty the Trash.
BUT this doesn't remove the Contextual Menu Items - unless you reboot your Mac (I did that, and the items was gone).