On Pesach, it's forbidden to eat, own or derive any benefit from chametz. I asked a renowned halachic authority here in Jerusalem about your case. He said that you are not allowed to deliver pizza during Passover. Since you earn wages by doing so, you are thereby considered to be deriving benefit from the chametz.
By the way: If this pizza shop delivers on Passover, they probably also put meat on some of their pizzas. If so, you may have to find another job. You see, milk and meat that is cooked together is similar to chametz in that you are not allowed to derive benefit from it. You should consult with the nearest Orthodox Rabbi about this issue, or get back to us.