Hair ladies I need help

My sister bleached her hair piss yellow and then "dyed" it with coolaid but she got a job and needs to dye her hair back to a normal color and wanted to bleach it again but I'm not letting her because she's going to melt her hair off. What would work best here, should she wash it wish dish soap or go to Walmart and get hair color remover? Would that even work even if it's not dye? It's still awful for her hair but it's not as bad as bleach. What color should she get in box dye to cancel out the blue? How does coolaid even work does it just stain the hair how do you even get this crap out???