How To Block Comments?

Since your question is placed in "About Blurtit" category, it makes me believe you are asking about How to Block comments at Blurtit.
You can stop anyone commenting at your shoutbox by keeping it to Friends only option and after that only your friends can give comments at your shoutbox.
But, You cannot ban anyone to comment on your answers or at commenting at your questions' answers. But, in case you find any comments offensive, you can report them to the moderators by using Report option.

If it is a comment under your answer that you are talking about, you can't, but, if it is offensive, rude, mean, whatever there might be there like that, then you can report it. Under a comment if there is one made, then you just click on "Report", and tell them why you are reporting it, and they, being the programmers will delete it for you. Hope this helps.

If only we could. I'm not sure why you are asking though, you are not a regular user.