Go to Start > Control Panel > Add or Remove Programs. In the Currently installed programs box, click on the program and then click Remove.
Also you can 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.