Make sure you fix the water leaks first to prevent mold from reappearing.
To get rid of mold use mold killing products like bleach, vinegar, hydrogen peroxide, baking soda, etc. Apply or spay these on the mold. Wait for 10-15 minutes and then scrub the mold on the walls until all the discoloration is gone. Let the affected area dry completely.
If the affected area is too large, call the professionals. Cleaning it on your own could be harmful.
You can contact Titan Restoration for mold remediation services on 480-649-5050.