I have heard a few ladies talking about how to remove the stains in the arm pits of shirts. They said that you need only add Dawn, Hydrogen Peroxide and baking soda together and rub it in on the stains.
The amounts of each are as follows:
1 tsp. Dawn, 3-4 tsp. Hydrogen Peroxide, 2 tbsp. baking soda
It’s as simple as that. You need to test it on a spot that is not too visible to make sure that the color doesn’t change on the fabric.