For some people, it may require a period of restructuring your life around other services before completing the process though. Here is one recipe for getting away:
First, get a browser extension that blocks the newsfeed. This will help reduce some of the psychological manipulations.
Delete all of their apps from your phone and other devices, including Facebook, Facebook Messenger, WhatsApp, Instagram, and Onavo.
Turn off all notifications from Facebook. If they don't stop sending notifications, start marking the emails as spam.
Download all of your FB data.
Start joining other, distributed communities to start replacing your online social life with something better: meetup groups, forums, IRC/Gitter/Slack/etc.
Whenever someone sends you a message on Facebook, immediately move the conversation to email or text message and tell them to use email or SMS to contact you, since you are moving all conversations off of Facebook in preparation for leaving the site.
Start deleting all posts, comments, and photos on the site. It can take a while, even with a script.
Don't post anything new on Facebook. Start a blog (using something like Metalsmith, Hugo, Hexo + Github Pages or Netlify) if you have an urge to post things online.
By that point, the pull of Facebook will have faded, and it should be pretty easy to leave the site and not look back.