bleach works great
Klenztone #! if all else fails: http://www.klenztone.com/
as a house keeperwe use bleech but macke sure to have a mask to cover your mouth and nose because the smell is strong
First of all if the spot is small use a wire brush and simple oven cleaner let it dry and rinse away oven cleaner works for all hard problems with concrete and stains and odor. Try it.
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