I just went through the process of canceling online my wife's 3/21 flight and there is no option to get anything but a travel bank credit. I looked at all the FAQ's and they all said travel bank, which for the small sum I was dealing with was not worth anymore trouble. I did not talk to an agent about it.

On the other hand, I also cancelled newer reservations with Delta and was immediately refunded the money to the card that was used to purchase the tickets.