How can I unpublish a report once published?

I selected to Publish to web for a report recently just because I wanted to see how it worked.  Just too easy.  Its great.

However, now I want to "unpublish" that report or remove access for anyone outside my organization until I am granted approval.  How would I unpublish a report from the web?

Note, there is only test data in it now, so not a big deal for the time being.

Thank you,