hair color removal

Layla is right. To lighten your hair you have to remove color pigments from it. So the pigment is already gone, and the only way to get it back is to dye it again. I had the same problem. I dyed my hair about the same color as yours but it was already so fried i didnt want to dye it again and risk damaging it. But my roots started coming in and it started to look a little bad:) So i used a semi-permanent color the same color as my natural hair color.
It took evened out the color and the good thing with semi permanent they don't penetrate as deep into the hair as permanent colors. So that means they will eventually wash out (mine is still pretty dark and its been about 3 weeks) but it is a gentler option. I want to redye my hair in a few months so thats why I used a color that will wash out, but if you want to keep your hair dark until it grows out you may want a permanent color(depending on the condition of your hair).

If you lightened your hair I think you have to put color on it not take it off. But I've never used hair dyes before except for rinses so I'm not sure.