Dying my dark and highlighted hair very light brown

So I had my hair dyed a very dark shade of brown (at salon) and it has been through 2 rounds of highlights since then. I’d like to dye it to my natural color which is a dirty blonde/very light brown. My hair still has some of the dark throughout it though. What would have to be done to it to get it to an even dirty blonde shade? I don’t want it to have dark pieces in it from the previous darker dye as it’s way darker than what I’d like. Is there any way this can be done? What process would this require