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.
Once the uninstall process is complete, reboot the PC and then start the application again. Look through the list to make sure it's gone forever. Typically, Revo removes everything for an application (temporary files, obsolete files, registry entries, folders, etc.)