Not for cancelling the outbound segment(s) of the CLT-NYC roundtrip, but to use the voucher for another flight. Since it's possible that the voucher would be for less value than the change fee, the voucher could effectively be worth nothing to you. But just not showing up for the CLT-NYC flight leaves you in NYC with no valid ticket home - so don't do that. Even a worthless voucher is worth more than having to buy another ticket home Sunday.

Of course, this all assumes we're talking about non-refundable fare tickets. If your CLT-NYC-CLT tickets are refundable you can just cash in the CLT-NYC tickets and get your money back.

Jim