The artist can't delete comments. To get them deleted you have to ask one of te site admins. That means not only does the artist have to be sufficiently bothered by the comment to take the trouble, but the admins have to agree the comment should be deleted. Personally, I think trolling comments say far more about the idiot making them than they do about my art - I leave them there. I like constructive criticism. I like a little ego-stroking, too, but I read every comment I get, and if someone points out a problem with an image of mine, I'm grateful for it. I know I'll never be among the best artists here, but I try. However, a comment like the one hmatienzo quoted above isn't criticism: it's a deliberate insult with no attempt to be helpful or constructive. It's a troll. If the artist wanted that removed, s/he has every right. That's uncalled for and unfair.