1. Log into your Google account. Under your profile name, click on “Account settings.”
2. Scroll down to the Services section and click on “Go to web history.”
3. At the top of the Web History page, click on the “Remove all Web History” button.
You can always return to the Web History page and click the “Resume” button to allow Google to resume collecting your search queries.
If you do not sign into your Google account, Daily Mail Online reports that Google can “track your searches via the computer’s IP address. The only way to clear your personal history is by signing in.”
Source: Daily Mail Online