How do I night wean?

I don’t really have much of a milk supply anymore. I started to introduce formula & whole milk to make up for it. He does drink it sporadically throughout the day in his sippy cup (no bottles).

He wakes up several times to nurse but I just don’t really have a supply anymore. My body can’t keep up at this point.

How do I wean him fully so that he’s not waking to nurse at night?