Full cancellations or exchanges are easy. Cancel - get your money back; exchange
-CHANGES RESULTING IN A HIGHER FARE MUST BE ADD
COLLECTED AT THE TIME OF REISSUE
-IF THE CHANGE RESULTS IN A LOWER FARE THE
DIFFERENCE MAY BE REFUNDED TO THE ORIGINAL FORM
OF PAYMENT WITHOUT PENALTY
Use outgoing portion and then try an exchange on the return can be more difficult. At least it was for me the only time I tried it.