First you have to clean the washer thoroughly. All signs of mold and stale water have to be eliminated. You can use bleach or dedicated washer cleaner detergent. The rubber gasket at the front door will have visible signs of mold first. Check if you have signs of mold, and clean them. Also, clean the pump filter area. After the washer is clean, you can use the hot water cycle and other detergents to get rid of mold and smell for good. Remember to keep the front door open between washes.