I believe to eliminate mildew we must get to the source of the problem which is poor air circulation and moisture. There are many chemicals that will kill it, but to eliminate it, that is the only way.
In outdoor areas, plants can be cut back and fences painted with a mildew retardant added to the paint. (see professional paint stores). Indoors, leaking pipes or poor roofing is usually to blame and should be investigated and repaired.