My site is live but not ready! How do I undo this action?

lit. one head, two feet 1 month ago Technical Answers 24

I'm still building the concept of the site and it's far from ready to go live, but it looks like I'm ready. I did a Google search on how to fix this, but all the information there must be old because I can't find a way to make the site private or revert it back to "coming soon" status.