There are a few ways that you can remove dried old blood stains, but the most effective way is to use a product called Oxyclean. Oxyclean is a powerful cleaning agent that can remove even the most stubborn stains. Simply add a little Oxyclean to a cup of water and soak the stained area for about 30 minutes. Then, use a brush or sponge to scrub the stain until it is gone. If the stain is still visible, you can repeat the process.