To remove stamp ink from hair, you first need to dab nail polish remover on to the ink stains for a period to remove the excess visible ink. After this, spray your hair with hair spray until it soaks completely. Then, get some paper towels and press the hair in between them from both sides. You can continue applying the hair spray until you are convinced that all ink has finished completely. Then, wash your hair with a mild shampoo.
If you have dark hair, no problem, if you have light hair, now's your chance to add some fun streaks of color... See your hair stylist. Don't try anything stronger than shampoo or you can end up with a clump of mattress stuffing.