Wipe down the shower seat after each shower. Mold and mildew will form if moisture is left on the seat for long periods of time. Keep the shower seat dry to prevent the growth of mold, which will ruin the plastic.
Fill a plastic spray bottle with 1/4 cup white distilled vinegar and warm water. Spray down the shower seat with the vinegar cleaning mixture and wipe with a sponge. Rinse with warm water and dry with a towel. Use this vinegar spray once a week to help keep mold away.
Make a baking soda paste for visible mold and mildew. Mix 1/4 cup of baking soda with a few tablespoons of water to make a paste. Add water until it becomes a thick paste consistency.
Use a sponge and wipe away visible mold or mildew stains with the backing soda paste. Rinse with warm water and dry with a towel.