Revert back to Opus media player

I can't seem to find the answer here on the forum or through the help file, my apology if it is something I missed. I'm trying to revert back to the opus media player for avi files. I had associated ONLY media player classic to open these files types before, but now want to go back to the opus player, how can I do that, anyone know? thank you..

Easiest way is to use the Open With menu and select "C:\Program Files\GPSoftware\Directory Opus\d8viewer.exe"

Thanks, all done..