can salon lighten over box color

They will be able but either they'll have to remove the color or bleach it out, becuz most of the time, color doesn't lift color, tho some salon's dye's w/ stronger ammonia apparently do, according to behindthechair.com. Since u only wanna go a few shades lighter, they will prob check the condition and texture of your hair, and if they bleach it they should only use a mild bleach and not leave it on for so long since ur not aiming to go platinum! Then they'll prob rinse that out and apply a shade of ur choice, in demi- or semi-permanent. But if they use a color remover, they'll then proceed w/ applying a permanent dye w/ 30 vol. developer to ensure the correct level of "lift" to take r hair to the target color.