If bleached hair turns purple, that means that the base color is purple. There are two ways this can occur. Either there was a bluing agent to prevent a brass color or the high-lift formula had a blue base.
If the culprit is the bluing agent, washing the hair with a clarifying shampoo should remove the color. If there is still a blue tint, then buy a 30-volume peroxide. Mix this in equal parts with shampoo. Make sure to condition after. If this is due to the high-lift, use a light color level. Use a color lift with a yellow base to counter the color in the hair now. Combine 1 ounce of this with 1 ounce of a 20-volume peroxide and an ounce of conditioner. Apply to the hair for 10 to 15 minutes and then rinse.