I have had good luck with rubbing alcohol, dab it and it should just rub right off. In a pinch I have even used hand sanatizer with great results. Note that I have not tried this on leather but it works perfectly on clothes. You can also try mr clean magic eraser, again I have not tried on leather only walls (I have a 2 year old who just doesn't get the whole you only draw on paper bit). Good luck.