I fed my first until 4, so I get it 
If you want a gentle way (ie without conflict) I would try shortening the duration of feeds. So avoid, distract, offer replacements - but if he is really insistent that it is milk that he wants, say okay but we count down from ten. Latch him on, count down from ten, that's it. You can shorten this to three - IME once they get to the counting to three stage, they don't need it any more. They are doing it out of habit or because they can. Once we got to three, DS1 self weaned pretty soon after that (as in, he was ill so I actually offered it and he refused.) If you think even a ten second feed would be too brief for him, try letting him feed until the letdown comes (if you even get one any more - I'm not sure I did) or until his sucking slows down and then count down from 5/3 to end. You can then bring the countdown earlier and earlier into the session once he's comfortable with that idea.
OTOH - my big nursling is now 11, and in hindsight, I think I should have been less "gentle". I do not mean that I should have been authoritarian or punitive, because I still don't believe those approaches are helpful, but I feel like avoiding conflict all the time was actually not the best way to go about things. It served my own conflict-avoidant nature very well, but it didn't necessarily work well in terms of promoting a good relationship with my child long term. I have been reading a lot of Janet Lansbury (who calls herself "respectful" rather than "gentle") and I find that her philosophy is totally congruent with the beliefs that led me to gentle parenting, but one thing she's much better on is boundaries/conflict and the idea that it's OK to set boundaries for your own self care. Very interesting read/listen (she has free podcasts and transcripts them as blog posts).
So I think the respectful way would say OK, no, there's no easy way to do this without conflict, but that's OK. It's not a bad thing to make a decision that your kids would disagree with. If you feel that it's time to stop nursing, then decide that, and feel (or at least act) confident about it. Yes, he might be upset about it, of course. It's something that's been very important to him. You must acknowledge and allow him to express that upset. But it's actually more respectful to trust that he will experience these feelings, work through them (with your comfort if he wants it, of course) and ultimately be okay, than to fear that he might not cope with that upset, and hence delay the decision. That isn't really helpful to him (it might be nice for him, but that's not the same) and it's definitely not helpful to you, if you are not happy with how things are right now. If you keep nursing past the point where you're not happy with it any more, that isn't really being respectful to him either, because you will build up resentment and annoyance about feeding, and that isn't a place that is healthy for your relationship.