I think advice to drop this feed at 6 weeks is one of the things that may have been changed if Tracy was still around. Your LO is doing fantastically at 6 weeks to only be having 1 feed from the DF to wake up! There is a big growth spurt around 6 weeks and they do still need that nightfeed for a good while yet - remember their tummies are only the size of their fists and need filling frequently, even at night.
The most important thing with EASY is to follow your babies cues, if he is waking hungry at night you need to feed him, especially as he is so little. You may find he starts to sleep through by himself and not wake for that feed if he does and is gaining weight ok then that's great but I wouldn't do anything to activly wean it, you are better off getting him fed and back to sleep as quickly as possible.
Most babies will still need a nightfeed until 6 months or so - when solids are established. To be doing at least one feed until then is totally normal. When they get a bit older they may well only need a DF or a nightfeed but many still will need both. My DD only had a nightfeed (wouldn't take a DF) and we actively weaned that at 8.5 months when she was eating well and taking good amounts of milk in the day.
HTH!
Laura