What happens next?

How to lighten dyed hair
Rinse your hair with hot water.
The heat will open up the cuticles, allowing more of the dye to be stripped out. Thoroughly saturate your hair, in either the shower or over the sink.
Wash with a non-color-safe clarifying shampoo. The shampoo should be used immediately after you undergo your unsatisfactory coloring, and should strip some of the new color from your hair.