Other YouTube users can post comments on your videos and your channel (if the Discussion tab is enabled for your channel). Since it's your content, you have some tools to moderate the discussion.
Take action on comments. Click the arrow in the upper right of a comment on your channel or video to see your options.
Remove - Takes down the comment from YouTube. If the comment has any replies, they will also be removed. Note that if the comment was also shared on Google+, it will still be live there.
Report spam or abuse -Allows you to report comments that you believe are spam or abusive to the YouTube team.
Ban from channel - Blocks the user from posting comments on videos and your channel. You can remove the user from the banned list later in your community settings.
Hold comments for approval. You can require approval for all new comments before they're posted to your video or channel:
Video comments - Find the video in the Video Manager, click Edit under the video, and click Advanced Settings. Then, under “Allow comments”, select Approved. You can also choose the default moderation settings for new videos in your community settings.
Channel comments - You can turn this on for your channel in your Channel Navigation settings.
When someone comments, you'll get a notification as well as a blue banner on the channel or video letting you know there are comments to approve. You can then review the comments to approve, delete, or flag them for abuse or spam.
Spam filtering. If someone leaves a comment that looks like spam, a blue banner on the channel or video will let you know. You can then review these comments to either delete them or approve them if they're not actually spam.
There are additional tools available to help you proactively moderate comments in your community settings .