Or maybe I'm wrong...
Its actually really easy. In the environment file, it has something like
$Sky::fogColor 0.41 0.6 0.90 1.0
^This environment already has VERY LITTLE FOG
Just set the last value to 0
$Sky::fogColor 0.41 0.6 0.90 0
Note: I am just looking at code and taking guesses. I may be completely wrong.