While negative comments and critiques might be hurtful, or angering, at first, I think they do have a place in any open forum like this one. If you put your writing out there for the public to see, then a negative reaction is just part of the deal. Much like if you're a celebrity, you are just going to have to come to terms with comedians eventually making fun of you or tabloids snapping an embarrassing picture. We might not like it, but that isn't going to make it go away.
Having said that, if the comment is blatantly insulting and rude, I don't think any less of an author who deletes the comment. On hubpages, the comments are a part of the article we've written, posted on an account we control. We have every right to remove something we dislike.