On March 1st, Google will implement its new, unified privacy policy, which will affect data Google has collected on you prior to March 1st as well as data it collects on you in the future. Until now, your Google Web History (your Google searches and sites visited) was cordoned off from Google's other products. This protection was especially important because search data can reveal particularly sensitive information about you, including facts about your location, interests, age, sexual orientation, religion, health concerns, and more. 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.
Here's how you can do that:
1. Sign into your Google account.

2. Go to https://google.com/history

3. Click "remove all Web History."

4. Click "ok."

Note that removing your Web History also pauses it. Web History will remain off until you enable it again.
If you have several Google accounts, you will need to do this for each of them.