I didn't quit caffeine, but I cut down massively by keeping it in a Zojirushi mug that keeps it hot all morning instead of drinking from a regular mug. Because it stays hot, I just sip it, and that way I only drink one mug in the morning and occasionally one in the afternoon, instead of the 3 or 4 mugs I would drink previously.
This is an interesting technique. When I first started working in a place that had lots of free/good food, I was worried I'd gorge. Instead what I found was that knowing I'd always have access to good/free food meant I didn't feel the need to overeat ever.
hah! when I worked at a place that had free food I would be good until about 3pm, when I'd gorge on terrible snacks because I'd used up all my willpower coding during the day