you don't want to bleach it.. that's not going to work. no kind of bleach is going to do what you want to do.
they sell color remover with the dyes at the grocery store.. I've not tried it, so I don't know how well it works. as much as you seem to care about this shirt, you don't really want to use grocery store dyes though.. in my experience the colors are never very pretty or very fade-resistant.
here are good instructions for dying a whole garment a solid color. that's also where I'd go for a good quality dye.