Don't offer don't refuse is not a weaning technique, IMO, it's just what you naturally end up going to once they're older and get all their necessary calories from solids. I've never known anyone to actively cajole their toddler into a feed!
If you want to wean, you have to make restrictions and refuse sometimes. That will generally involve things like changing aspects of your routine, distraction, or replacing whatever aspect it is they get from BF with something else. Whether that's replacing with milk from a cup/bottle, giving them focused attention (sometimes BF can be a bid for connection with you), or replacing with a different soothing action (sleep, tiredness, upset times).
Or you can increase the interval between feeds - use other techniques/distraction/etc until a certain time period has passed.
Or you can reduce the duration of feeds. Cut them off after a certain number of minutes/seconds. I find this is tricky until you're right in the final stages of weaning and already down to microfeeds (under a minute). Because normal feeds can vary so much, so one time they'll feed for 6 mins, another 20, another 14, another 7, etc, with no pattern to it so it can be hard to consistently shorten them. But maybe some toddlers have a more consistent pattern? I don't know, it's not my experience. I always strongly suspect this is just a port of "Give them half an ounce less each night" and probably just doesn't work for breastfeeding because breastfeeding isn't like that.
If it's during the day, I tend to find restricting it to certain times helps a lot - it's clear and they know what to expect. So if you say no milk now, but you can have it at nap time, for example. Or not here, but when we get home. I tended to offer cow's milk in a cup if they kept asking. Sometimes they would like that and sometimes they'd say no.
Bedtime - don't ask me as I'm still feeding my 2.9yo at bedtime and can't stop 
DS1 stopped eventually by himself. But there is loads of advice about weaning off feeding to sleep, breaking the feed to sleep association, changing the bedtime routine to avoid feeding (or simply separate it from sleep at which point you can then later drop it) - you could look up these terms and see if that helps.
Stopping overnight feeds is normally called nightweaning which makes it really easy to search for advice. My accidental night weaning success was being really strict with myself about not bringing him into our bed until 1am, then 2am, then 3am, then he just went through. Also instigating a delay before feeding. So I'd pick him up and just cuddle him for 5 mins before actually allowing him access to the boob. I'd use whatever soothing language I would normally use if I was struggling to open my bra or whatever, so he knew it was coming but just not quite there and then the idea was to extend the delay - I never needed to. If he does wake in the night he goes back off with a cuddle now, even if he asks for milk, he has a cuddle and falls asleep happily before he gets there.
I think it can be really helpful to see these three different times as separate weaning challenges, rather than trying to stop it all in one go. Decide which part you want to cut out the most - day feeds, night feeds, feeding to sleep - and focus on that. Sometimes you'll find that cutting one leads to one or both of the other two stopping or reducing as well. Sometimes if you're struggling to wean at one specific time, swapping to a different time to focus on works better. For example, if you can't nightwean, try stopping feeding to sleep or reducing/stopping feeds in the day instead.