Cleaning Plastic Shower Stall Floor . Remove all bottles, soap, razors, and accessories from your shower. Clean shower stall walls with a mix of 1 cup ammonia, ½ cup white vinegar, ¼ cup baking soda and 1 gallon of hot water. How To Clean An Acrylic Shower or Bathtub Acrylic tub, Fiberglass from www.pinterest.com.au If necessary, use a nonabrasive brush or cloth to scrub the stain. Rinse your shower with warm water, and repeat as needed. As you do, apply a small amount of pressure to let the juices out.