Rocketfish -HDMI no longer works

I have a macbook air 11″ so use a Rockfish adaptor-HDMI to project onto my TV so I can see properly.
After loading Kodi, this function no longer works even though I am offline.
Can someone please tell me if there is a way to overcome this? If not, can someone tell me how I can uninstall Kodi so I can revert back to where I was .
Thanks,.