Mildew, mold and leaf stains on marine vinyl, boat upholstery or leather furniture often cannot be completely cleaned, but they can be concealed with Rub ‘n Restore®. These stains must first be treated to kill any living fungus, so it does not grow through the new finish.
For leather, kill mold or mildew with denatured or rubbing alcohol.
For marine vinyl, you can use alcohol or a solution of 10% bleach in water. Some folks report success with Marine 31® Mildew Remover.
Never use abrasive cleaners on leather or vinyl.
If mold or mildew is growing on the interior stuffing, the pieces should be treated in a sealed ozone chamber. Contact a local fire or flood restoration company. Otherwise, the piece will require replacement or reupholstery.