Take out deodorant stains - how?

If it's the yellow underarm stain, don't use chlorine bleach - it can make it darker. Soak the shirt in warm water with an oxygen bleach (the powder kind) for an hour or so, then scrub a baking soda paste into it and wash. It comes back because it's build-up from antiperspirant and sweat, not a one-off stain. Letting the deodorant dry before you get dressed helps more than you'd think.