If you want to keep Google from combining your Web History with the data they have gathered about you in their other products, such as YouTube or Google Plus, you may want to remove all items from your Web History and stop your Web History from being recorded in the future.
To learn how, go here: https://www.eff.org/deeplinks/2012/02/how-remove-your-google-search-history-googles-new-privacy-policy-takes-effect
It isn’t easy because they don’t want it to be. Here’s what to do:
Sign into your Google account.
Click on your name. A box opens up:
(Your Email address)
Go to “Account Settings”
Then go to “Services”
You will see:
Delete entire Google account------ Close entire account and delete all services and info associated with it
View, enable, or disable web history----- Go to web history
Go to “Go to web history”
Click "remove all Web History."
You will see “Web History is paused” and “Your search history is currently empty”