Cathy, get a vinyl inflatable
children's wading pool, fill it will warm water
and plain soap (like Ivory flakes aka Ivory Snow) *not* detergent. If you can't find plain soap, use a "no sting" shampoo. Then drag the sails in, let them soak a bot, and scrub with a soft bristled nylon scrubbing brush. If the mold won't come off, you'll need a bit of bleach of oxy cleaner to get the rest of it. Check around online for recommendations but use as little as you can, and wash it out thoroughly, because bleach weakens fabrics.
If the room is well-ventilated and DRY, mold won't grow there. Apparently the mold is coming in with the airflow and the room is neither warm enough nor dry enough to stop it, so throughly cleaning
and DRYING the sails, then bagging them for storage
, my be better for you. I'd look into putting a mildecide into the storage bags, or getting large plastic bags (or making them up from poly sheeting and duct tape) and then bagging the sails, along with dessicant bags, for storage. Sealed up with dessicant, they just wouldn't be able to grow mold--assuming they were clean and dry to begin with.