First I sprayed the moldy surface of the shower with a vinegar & water solution (half 'n half) and let it stand overnight.
Next day, I mixed together the vinegar, baking soda, and tea tree oil in a small cleaning pail. Using a cloth wetted with the cleaning solution, I wiped down the shower. The solution quickly and easily removes the mold and requires no rinsing, as the vinegar and tea tree oil are natural mold inhibitors. Voila! Clean, mold-free shower!