In Google Webmaster Tools, you can disable your Google Sitelinks from showing up in the Google search results. But according to a Google Groups thread, it doesn't work.
Personally, I don't know anyone who doesn't want Sitelinks to show up under their search results. So I have never really heard of anyone wanting to disable ALL their Sitelinks from showing up. But this is the first report I have seen of such a request and it shows that it is possibly not working right in Google Webmaster Tools.
The webmaster asked, "i've disabled my sitelinks 5 days ago but they are still on, how many days does it take to see my sitelinks change?" In which JohnMu from Google responded, "I've passed this on to the team, thanks for posting." That response makes it sound like a bug to me.
Of course, webado replied, "Hah, some people would sell their first born to see sitelinks for their site .... ;)" Very true.
Forum discussion at Google Groups.