auto delete all comments?

For another site that I’m working on, I have it set so that no comments are used at all. I’m basically using posts as announcements so no comments are necessary. Even though comments are turned off, and I don’t even show anything below the post if you’re inside the post I’ve still gotten some spam although it gets caught in moderation. What would be the best way to prevent these comments being sent to moderation assuming I have no need for comments whatsoever.