To remove butter stains from fabric, first scrape off the excess butter, then treat the stain with a pre-wash stain remover. Wash the fabric in the hottest setting possible in the washing machine.
For stubborn stains, try pre-treating the fabric and allowing it to soak in warm water prior to washing. Since butter stains are grease-based, a grease-fighting dishwashing liquid may also help remove the stain. Apply a few drops of the liquid directly to the stain and rub it in. Allow it to absorb prior to washing the fabric.
To remove butter stains from upholstery or carpet, sprinkle some baking soda or cornstarch on top of the stain after scraping off the excess butter. Allow the baking soda to stand on the stain for at least 10 minutes before using a vacuum to remove the excess. Blot the area with a white cloth dipped in dry-cleaning solvent. Repeat as needed until the stain is gone.
If the baking soda or cornstarch does not successfully remove butter from a carpet, another option is to try a solution of dishwashing liquid and vinegar. Mix one tablespoon of vinegar and one tablespoon of dishwashing liquid with two cups of warm water. Use a sponge to apply the solution to the stain then apply cold water with another sponge. Blot with a cloth until dry.