You are not seeking a name change, but a passenger change. That simply can't be done.

Your only option is to obtain the most value from the cancellation and the best bet there is to wait until the day of travel and cancel just before the check-in deadline. If the flight is cancelled or substantially delayed (changed), you have the option of a full refund. Same if there is a significant change between now and the scheduled date. Otherwise, it's just the taxes.

As others note, depending on the reason for the other person not coming, it may be possible for their or your (since you paid for the ticket) to claim. That will depend on their reason and the specific policy involved.