Originally Posted by
samdori
They do have miles redemption (UA, US, Alaska, Frontier, and Airtran). You probably have to close your account and rejoin under the program you want. I think you can only have the option to redeem under one airline at a time.
IIRC, if you email them, they can change it for you. It used to be only if your geographic location changed, so that your preferred airline was no longer a viable option near you, but they might allow you to change based on DL's exit.