On January 24 Google announced that as of March 1 it will begin combining your Google search activity with the data it has from your activity on its other platforms, e.g. YouTube and Google Plus, for the purpose of create targeted advertising and reminders. You will not be permitted to opt out. But the Electronic Frontier Foundation, which says the combined information can reveal sensitive information such interests, sexual orientation, religion, and health concerns, shows you how to delete your Web history. 1) Sign in to your Google account. 2) Go to https://www.google.com/history), click “remove all Web History” and click OK. Your Web history will remain off for that account until you enable it again. If you have more than one account, you have to repeat the process for each one. Follow this step-by-step guide if you want to see the screenshots.
HT: ABA Journal