People treat friendships differently from romantic relationships, and it always seems absurd to me that we hold our domestic partners to wholly different standards than we hold our friends. For instance, sometimes people will put up with longstanding emotional abuse from friends in a way they never would from their romantic partners. "Friendship" to some people, means an unbreakable commitment, but it's really not. Friendships, like any other kind of relationship, can end. People change, grow, or become mean and distant. And like anything else that no longer serves you, it's okay to end a friendship.
1. Don't be sentimental
Every friendship, no matter how toxic it is, has its good moments. Of course you have memories of fun times, and laughter, but don't romanticize your past, as tempting as it might be. If you can learn to leave the good times in the past, and take them for what they are (isolated rays of sun through torrential raining shit), you can walk away. Don't be sentimental about those who don't deserve it. Save your fond nostalgia for people who enrich your life, and work towards building memories with them rather than dwelling on meaningless ones.
2. Be honest
Be honest with yourself, and with your friend. Don't phase someone out. That fucking SUCKS. It also makes you just as toxic as them. The only exception would be for casual friends/acquaintances/party pals who wouldn't find anything amiss if you weren't at the bar on a Friday night. But for the friends you talk to and see regularly and intimately, it's important to communicate your desire to end the friendship. That way they know your agenda and won't pursue you, or be hurt by you ignoring them suddenly.
3. DELETE, DELETE, DELETE
I'm a big proponent of actually deleting people from your life when you decide you want to delete them from your life. Because any sort of lingering social media presence is only going to serve as temptation to stalk, which is only going to lead to you feeling bad which negates the purpose of divorcing from your toxic friend in the first place, which is to make you feel good. Delete their phone number, past texts, Facebook, Instagram or any other way in which you're digitally connected.
4. Make a conscious effort to make new friends
When you end a romantic relationship, people around you will often urge you to date again. The same goes with purging a toxic friend. Find new friends, or invest more time in healthy, existing friendships. Feeling alone, or like you've lost someone, sets you on a dangerous course to regress into old, bad habits. Surround yourself with love and happiness and you'll be less likely to miss the person who was nasty to you.
5. Don't re-engage
If the toxic friend you're trying to cut out comes sniffing you out, trying to create drama, don't engage. If another friend comes to you and tells you that old friends has been spreading talk about you, ignore it. If you get angry, guilt-applying emails or texts, politely decline to engage with them. A friend whose natural pattern it is to create drama knows how to rope people into their theatre with manipulation, so be clear with your intention to separate yourself from the melodramatics. It's important to walk away firmly, and not being tricked into defending yourself when your toxic friend tries to stir up some shit.
6. Put yourself first
Chances are, in a toxic friendship, you're used to putting the needs of your friend first, often sacrificing your own happiness and needs. In order to truly cut someone out of your life you need to be prepared to put yourself first, for once. Think about what YOU need and what will make YOU happy in the long term, and do that without any of the guilt your friendship dynamic normally would have you attaching to serving yourself.