1 Make a paste using the baking soda, meat tenderizer and cold water and apply to the stain. 2  Let it set for 15-30 minutes. 3  Scrape away and rinse with cold water. 4  Avoid using warm water, it speeds up the setting process and makes the blood stain more difficult to remove. 5  If nothing else works, try spitting on it. Blot the area with a clean cloth, working from the outside in to remove the stain along with as much of the hydrogen peroxide as possible. 2  Repeat steps 4-5 as necessary. 3  If the stain still wonât budge, mix 1 tablespoon of ammonia with 1 cup of water and apply using the same method as above.