Unplug your slow cooker.
Wet a clean sponge with warm water. Squeeze out excess moisture.
Place one to two drops of dishwashing detergent on the damp sponge. Scrub the inside of the slow cooker with the sponge to remove any odor-causing stains.
Rinse the sponge with warm water. Wring out the sponge and wipe the inside of the slow cooker to remove the detergent.
Dry the interior of the slow cooker with a clean dish towel.
Sprinkle baking soda over the interior bottom of the slow cooker. Place the slow cooker inside a large plastic bag and seal the bag.
Leave the slow cooker in the plastic bag overnight to allow the baking soda to absorb any remaining odor.
Take the slow cooker out of the plastic bag. Empty the baking soda into the garbage can. Wipe the inside of the slow cooker with a damp sponge to remove baking soda residue.
Dry the slow cooker with a clean dish towel.