But actually, simple home remedies can remove the odor and make your mugs fresh again—without spending a rupee. 4 / 9 Baking Soda Method: Baking soda works wonders, too. Mix baking soda with water in the mug and leave for 30 minutes. This prevents the smell from returning and keeps the mug fresh. Mix a little in water, leave it in the mug for 30 minutes, then rinse.