How to Delete Your Google Web History
1. Sign into your Google account.
2. Click on your name at the top right corner of the screen and then select Account Settings.
3. In the Services section, click the Go to web history link adjacent to the View, enable, or disable web history option.
4. Click Remove all Web History at the top of the screen to remove all instances of your browsing history.
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5. You may be asked to sign in again to confirm that you are the owner of the account.
6. In the next screen, click OK to confirm deletion of your entire web history.
By deleting your entire web history, you are also in fact stopping your web history from being tracked in the future.
However, you need to remember that Google will continue to gather your browsing data for its internal use. You just will not see search results based on your personal browsing history.
You can also sign out of Google while browsing but remember that your browsing preferences will still be tracked via your IP address. And you can resume your search history anytime by heading back to your Account settings, navigating to the Web History settings page and clicking Resume button.