What do you think about ending a friendship out of the blue?
Do you think you will change your mind about that?
I don't care, I'm breaking the friendship
Breaking up a friendship abruptly without explanation is mean. You at least owe it to the person why you're ending the friendship so they know why.
I'm not going to explain, I'm doing what I want
I think that is unfair to your friend. You should let them know why you want to end the friendship. It is the polite thing to do so they don't always wonder if they did something wrong.