Sometimes we become doormats in our relationships, hoping our loved ones will learn how to treat us better. We know we deserve better, but we timidly swallow our feelings for fear of rocking the boat. If you have a friend who's particularly disrespectful, decide that you won't take it anymore. Declare to your friend that he will either treat you as you deserve to be treated or lose your friendship. If your friend doesn't change, remain true to your word and end the relationship. And even though you've said goodbye, appreciate your ex-friend for inspiring you to finally stand up for yourself.
Think about it carefully. Ending a relationship with a friend shouldn't be done on the spur of the moment. Did your friend's disrespect just begin, or is it something you've always put up with? If you've always put up with it, consider why are you ending the friendship now. Answer these questions honestly within yourself. Admit that you've decided you deserve better. Be proud of yourself for determining to remove yourself from a toxic situation.
Do it in person. Even if your friend is disrespectful, give the friendship the respect it deserves. Treat the situation the way you'd want to be treated. Ask your friend if you can come over, or if she can meet you somewhere private so neither of you will be embarrassed if emotions escalate. Meet her wherever you can leave freely once the conversation is over. Ending the friendship at your house gives her the chance to disrespect you by remaining in your space longer than you're comfortable with.
State your reasons clearly. Don't go back and forth as if something is being negotiated. You've already made a decision; you're simply telling her so the two of you can be on the same page. Don't reiterate your reasons. If your friend keeps asking why, say, "I've already told you."
Don't bring up the past. You can't change what happened. Now is not the time to make any final points or rehash prior arguments. Acknowledge that what's done is done and there's no going back. Stand firm in your decision.
End on a mature note, if possible. Explain that you've learnt valuable lessons from your friend that you will carry into the future. Thank her and wish her well.