Removing and Preventing Mold In Your Humidor Simple solution: IONIZED SILVER (aka) Colloidal Silver And we Monkeys know how to make our own, don't we? Just wipe down all the surfaces when you season the humidor or on a periodic cleaning schedule. Another possible solution: UV light (220-270nm wavelength, in particular 254nm) Currently, I can only locate UV lights in this wavelength for sterilizing equipment, but nothing practical and suitable to place inside a humidor. Remember, you will need to be careful and always remain within the guidelines of "safe for humans" and not resort to cleaning and sterilizing with harmful chemicals. As always, it's good practice to keep a healthy RH level and temperature between 60-73, ideally.
I've found that sunlight exposure every couple of years works too...but I've not ever had a mold issue to begin with.