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.
Additionally, if the application still refuses to uninstall, use Combofix and run it. Download and install the package and it should be removed after the scan. The Internet connection as well as running applications will be turned off or closed.