I did the same thing I dyed the ends of my hair red for the summer with my friend the internet how to's said about 2 weeks its now been over a month and I wanted it out for school picture day I did some research and I made my own solution; fill a mug halfway with water and the other half hydrogen peroxide (warning hydrogen peroxide will burn your hands so wear gloves) then add about a tablespoon of baking soda and a tablespoon of dish washing liquid. Add some conditioner to the mixture (dandruf conditioner works better) now mix it up with a plastic spoon. (WARNING do not use metal, the hydrogen peroxide will wreck it) now dip the dyed hair in it and let it soak for 5 minutes then leave your hair dripping wet and wrap it up in plastic wrap and secure it with an elastic now sleep with it like this and in the morning have a shower and unwrap your hair you will see the water turning red do this every night until its gone. Hope this helps.