There are many ways to lose a friend. Sometimes its because you might not be as compatible as you thought or sometimes can accuse of something you know you would never do. i know almost everyone has a friend who wasn't really a friend and has stabbed you in the back (figuratively speaking). Anyway sometimes there is a lot of anger. You may have to be upfront about ending things if your friend has not treated you well. losing a friends can be painful. find some some way to not see them or interact with them much.
1. Try not to interact with them as much.
You might just not be clicking as you once were. They may get the hint that you're not interested in keeping up with the friendship. Try to avoid answering their text or liking their posts.
2. Be more careful with picking friends in the future.
If you broke things off with a friend who was toxic (i.e a jackass who only cared about themselves and didn't want to hear about anything you did), see this as a learning experience (and actually learn from it) there were plenty of warning signs that you ignored. Like were they always kind of mean to you, accused you of stealing something of theirs, and they always almost always were prone to talking about his or herself.
3. Don't pick a fight.
Take the kinder respectful way out of a friendship. If you have a lot of mutual friends or are likely to still see each other slowly fading out will make stuff less awkward. But if you've got one of those friends who are too self absorbed that they cant read the signs of you X-ing them out your life, be honest.
It doesn't have to be cruel but at least they'll finally get the hint of why you no longer want to be friends with them.