Ventilate the area. If there are any windows or doors near the humid space, open these for as long as possible to replace humid air with fresh air. Opening windows and doors will also keep a constant current of fresh air circulating in the space.
Install a dehumidifier in the space. Dehumidifiers work by sucking in humid air and removing moisture from this humid air, which is stored in a tank and later drained. Dehumidifiers can be purchased in several capacities for different size rooms and humidity levels. Large rooms or rooms with dense air will need dehumidifiers with more power.
Turn off humidifying devices in the room or in the area. Many appliances release heat and can significantly add to humidity within a space. Shut off clothes dryers, gas-burning heaters, furnaces and anything else that produces heat when in operation. Look for anything that is plugged into an electrical socket that is not in use.
Put up curtains or window blinds on any window in the space. Bare windows collect and pass on heat into a room, much like a magnifying glass, making the room hot and humid. Curtains, blinds and shutters will repel this heat and help cool down the room, which will in turn make it less humid.