The DF should be elliminated by reducing the intake from the DF a little at a time and, like the other poster said, increase the daytime feedings by the same amount. So take 1/2 an ounce (or more) out of the DF only after adding that 1/2 an ounce to the daytime feeds. Do this for three days then reduce it a bit more for three more days, etc, until it's gone altogether. He will continue to get the same amount of calories, but during the day rather than at night.
You will probably find that he still wakes during the DF hour, even after you have weaned him completely, that is when you will need to soothe him with other methods until he doesn't wake at all anymore. We are in the process of doing this with the middle of the night feeding for our 16 week old. He doesn't take anything anymore, but he still wakes and needs comforting out of habit. It's only been three days, so we haven't quite cracked it yet, but I look forward to the day he sleeps through!!