I need to block a user from commenting on my blog. He was very well-behaved at first, so I approved his comments, but now he's become abusive (borderline stalking) and I can't figure out how to un-approve him. I don't want to turn off all comments--just his. Because my site is youth-oriented, I have quite a few young readers and I want to let them keep commenting without exposing them to his abuse.
He always uses the same screen name, blog address, etc. to promote his own work, and will likely leave my site alone if he can't self-promote, so is there a way to block an individual user from commenting on my WordPress site?
Thank you very much in advance for your help!