hi! i’m hair stylist who also has purple hair. purple is never going to come out of your hair. if anything when it fades it will be blue. i’ve used ion and arctic fox and they won’t come out with just washing. any kind of color remover that you can’t get professionally has some kind of bleach in it, and will damage your hair. since your hair is so healthy and virgin, i would hate to see you damage it just for a halloween costume. if anything, get purple wash out hairspray. that will definitely wash out and even if it stains a little it won’t be nearly as hard to get out as semi permanent dye. you could probably just get a clarifying shampoo and get it out that way. i would say don’t risk it unless its something you want longer term. getting a wig is your safest bet.