Cut a lemon into quarters. Rub lemon wedges over all the moldy areas in shower, making sure to get into crevices and corners. Let the lemon juice sit on the mold for 15 minutes.
Reapply lemon with fresh wedges and let it sit for another 15 minutes.
Scrub the affected areas with a scrub brush, then rinse the lemon juice away. The mold should be gone, or greatly reduced, due to the acid in the lemon.
Put on gloves to protect your hands, then pour laundry bleach into a spray bottle.
Spray the bleach onto all moldy areas in the shower. Run the bathroom fan or open a window to reduce bleach fumes. Let the bleach sit on the mold for at least 10 minutes.
Scrub the moldy areas with a stiff brush, then rinse with water. If mold remains, spray again with bleach and let it sit for 15 minutes before scrubbing and rinsing.
Mix 2 teaspoons of tea tree oil with 2 cups of water in a spray bottle.
Spray the entire shower interior, particularly the moldy areas. Leave it in place for two to three hours.
Wipe the tea tree oil and mold away with a damp sponge. Tea tree oil is a natural antifungal that breaks down the mold so it can be easily removed.