Toenail fungus, like most kinds of fungus, thrives in humid, warm areas--closed-toe shoes provide a good environment for this fungus. If you've developed toenail fungus, it's likely your shoes are infected with the spores. Cleaning your shoes of toenail fungus is not difficult, but you must be very thorough. Recurrence of toenail fungus is very common--you can easily get re-infected from your own shoes. Make sure that the anti-fungal product you use touches all the inner surfaces of your shoe.
Place your shoes on a table so you don't have to bend over to clean them; protect the table surface with a towel. Remove the shoes laces, if applicable. You should open the shoes as much as possible to ventilate them. If the shoes are wet, allow them to dry in the open air, preferably in sunlight.
Spray an anti-fungal foot spray, labeled as effective against toenail fungus, inside the shoes. Make sure you spray deep inside to cover the toe areas.
Dry the shoes in the open air. If the weather is nice, leave them out in the sunlight, which helps kill fungal spores.
Spray the shoes again after they dry. This will kill any remaining fungus that may have survived the first spraying. Let them dry completely again, in the open air, under sunlight if possible.
Sprinkle an anti-fungal foot powder inside the shoes.