Preventing Google from sharing personal information, such as health status, sexual preferences, etc., gleaned from search habits is as simple as deleting your Web history. Now, you’ll have to do this for each Google account you have, but once it’s done, your search history will no longer be shared internally and externally. It will only be used internally.
Deleting your Web history is pretty simple. First, log in to Google account, click on the drop down arrow beside your login ID in the upper right of the page and select the “Account Settings” link. On the Account Settings page, scroll down until you see “Services.” Under services, click on “Go to Web history.” On the Web history page, click on “Remove all Web history,” then click OK, and you’re done.
As stated earlier, Google will continue to use information gleaned from search habits for internal use, which means it will also continue to gather this information, Google will no longer keep the information gathered from your searches indefinitely and some of it will become anonymous after 18 months.
Today is the last day that anyone who wants to keep Google from sharing his information across all Google products, with external vendors and other external recipients can do so by erasing all Web history. How much you enjoy customized search results may determine whether or not you think keeping your Web history enabled is worth the risk. Just keep in mind that all kinds of unknown individuals could be privy to your search habits.