The best way to teat a stain is to catch it while it is still fresh. Once it has dried up, you may not be able to remove the stain yourself. You will have to get professional help. Try this: spray denatured alcohol on the stain. Working your way from the outside going in, blot with absorbent paper towels until the stain is gone. You could also use nail polish remover, but first try it on a hidden area of the carpet to see if it will affect the colour.