Threatening behavior

Hi everyone! I need some advice on how to go about an issue. I previously had a discussion with a member on here. His behavior came as narcissistic and someone whom was in the wrong, but wanted to be right. He wanted me to agree with everything he was saying. I was very polite and respectful towards this person. He proceeded to attack me by harrasing me and using very hateful language. I want this person to be banned from the site because I know that Im not the first and last to experience that. What he did was not okay and he most definitely does not belong on the site. I do have his username saved. Any ideas would be appreciated. Thank you!