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.
Or you could go to the Uninstall a program in Control Panel to initiate the uninstall procedure. If it refuses to uninstall, then use the method above.