Cover any furniture or equipment that is nearby before trying to remove the fog. Most fog is produced with a chemical called glycol that will leave a thin film on anything in its path. When you try to spread the fog to remove it, it could get over nearby items and leave the film, so be sure to cover them as protection.
Open doors or windows near the stage. The biggest enemy of fog is wind, so even a light breeze coming in from outside can help the fog dissipate.
Turn on portable fans and point them directly at the fog. Since wind will break the fog up, artificial wind works just as well. Point the fan directly at the fog or if it is widespread you can use the rotation function on the fan to spread the breeze over the entire area covered in fog.
Turn on ceiling fans or air conditioning if available. Though these can't be pointed directly at the fog, they stimulate air circulation which will help break it up.
Wave cardboard back and forth to break up the fog. Though this is much more labor-intensive, if all else fails this will work to make the fog disappear.