How do I remove colored cake icing?
Frosting usually contains butter or shortening, or some mixture of the two; and so you do NOT want to rinse the stain first before treating it. Instead, start by gently scraping away as much stain as you can (plastic knives work well for this) to minimize the amount of stain you need to actually treat. Next, pretreat with liquid dishwashing detergent—a good liquid laundry detergent will also work well—to solubilize (break down) the concentrated butter/oil. To do his, apply a little directly to the stain and rub in. Wait 5 minutes and then rinse in warm water.
Now you can launder the item. Select the warmest water recommended on the care label using your favorite detergent and either ⅓ cup Clorox® Disinfecting Bleach for bleach-safe whites or Clorox 2® For Colors 3-in-1 Liquid for colors or white items with spandex. Allow the item to air dry and then check for success. This is important because residual oily stains can be hidden on a wet or damp item, and you’ll want to keep it out of a hot dryer to avoid heat setting a stubborn stain that might otherwise come out with a second treatment.