Fill a cup or bowl with lukewarm water and add two or three drops of alcohol-free detergent. Soak a soft rag in the solution and gently rub the gloves with it. Turn the gloves inside out and wash their interiors with the rag. Hold the gloves under a gentle stream of cool, running water. Rinse them just enough to remove any suds, but don’t completely saturate them. Rinse the insides then turn them right side out and rinse the exteriors. After rinsing the gloves, use a clean, dry towel to soak up excess water. Turn the gloves inside out again and squeeze the towel around them to ring out moisture. Then turn them right side out, towel dry the outsides, and hang them to completely air dry. Hang your gloves away from direct sunlight to air dry. When the gloves of are dry, apply a leather or glove conditioner to the leather palms. Use a clean, lint-free cloth to rub a small amount of conditioner onto the surface, let it set for a few minutes, then use another cloth to wipe the gloves once more. Use a baseball glove conditioner, leather shoe conditioner, or other treatment designed for leather.

Summary:
Rub the gloves with a solution of lukewarm water and detergent. Rinse the gloves under cool water. Soak up excess moisture then air dry the gloves. Treat the leather with a conditioner.