Try using Revo Uninstaller. Even if it can't uninstall the application normally, it will force it to uninstall by wiping out all traces of its presence from the system.
After that, try running AdwCleaner to make sure that there are no leftover rogue registry keys or toolbars in your system. After the application finished scanning, run it again and make sure the add-on doesn't appear anymore.
Additionally, run a copy of Junk Removal Tool. Download and launch it and let it remove the items automatically.