You maintain control over blog post comments by being given the ability to moderate them as they come in.
STEP 1: To see comments that require your approval, go to the blog post that was commented on. Scroll down to the comment and click edit.
STEP 2: If you chose Edit to approve the comment, click the Administration drop-down, then click Published.
STEP 3: Scroll to the bottom of this screen, complete the Captcha, and click Save to publish.
If you have any more questions, feel free to submit a support request here.