Originally Posted by findark

There is not supposed to be such a thing as "cancel and get future flight credit". With how messy things are it's entirely possibly someone might void the coupon and write you an ETC, but the former option is supposed to be the only one.

Originally Posted by United.com

Cancel your flight and rebook later:

On the united.com homepage, select "My Trips" and enter your reservation information to retrieve your flight
Select "Cancel flight"
Confirm flight cancellation
If you have future flight credit, when you return to the reservation, select "Use Future Flight Credit" to shop for new flights and apply the credit towards a new flight.