I've dyed my hair brown and I had to put a red in it to make it go brown but how do I get blonde back

Did you color your hair or did you have a professional do it? It sounds like if you put a red on it-your stylist may have used a filler to replace the missing pigment needed? You should not do anything on your own. Have your stylist evaluate your hair to see if it is healthy enough for a color remover or maybe just have her do a heavy hilite. Once you go dark you have to go back to light with patience. Remember this-once the integrity of your hair is compromised there is no going back. So before you decide to do anything discuss it thoroughly with your stylist. Next time consider using a demi permanent color to go darker because it is a lot easier to remove.