At long last Google now lets you turn off SearchWiki. If you don’t know what that is see my posting Begone Searchwiki. You first of all need to be logged into the Google account on which you enabled SearchWiki. Then go to Preferences and tick the SearchWiki box that says “Hide the ability to share, promote, remove, comment, or add your own results.” That’s the good news.
The bad news is that if you have promoted, demoted or deleted results from a search your changes will remain in place every time you log in to your Google account and run a search. You will have to re-enable SearchWiki, run a search and at the bottom of the results page click on “See all my SearchWiki notes”. From there you can undo all of your changes. Then go back into Preferences and disable SearchWiki.
For more details see Search engine land’s Google SearchWiki: You Can ‘Check Out,’ But Your Results Don’t Leave