If it was my channel we were talking about, then those comments are par for the course. But if I was running a positive kids channel like yours, I'm not sure how I'd handle it. I've never liked any form of censorship, but I understand the need to have a clean environment.
I guess I'd still confront them. I dislike how people think they can just post whatever they want without any regard for the person they are saying it to. I'd reply back and hold them accountable for their words. I'd ignore the part they said about my channel and focus on the way they are behaving. I'd pretty much send the message that if you're going to be rude to me on my channel, you're not going to get off easy. I wouldn't be rude, but I'd cut them off at every comment with a response until they either go away or change their behavior. It may create a negative environment, but it also may be encouraging to see rude people actually called out in a mature, assertive way for once. Then again, I'd probably run your channel into the ground without trying to if I was in charge.