Are you talking about the cobra fan settings in evilnat? You can go back and select any fan setting there. You don't need to do anything special. I think the disable fan control just reverts to Sony's stock syscon.
You can leave webman on syscon, and use the evilnat settings under cobra, or you can use webman and ignore evilnat's fan control completely. The upside to webman is that you can monitor and make changes from any device on your network.