How to Clean a Doubleclick Tracking Cookie
The Doubleclick tracking cookie is used by Google for ad tracking purposes. Whenever you visit a website with Google ads on it, a cookie is placed in your web browser by the ads and is used to track you across the Internet. You can erase this cookie from your computer by deleting the cookies from your web browser.
Remove Cookies From IE
Click on the "Safety" button in Internet Explorer.
Click on "Delete Browsing History" and then click on the "Cookies" option.
Click "Delete" and the cookies in IE are removed.
Remove Cookies From Firefox
Click on "Tools" and click on "Options."
Click on the "Privacy" tab or section.
Click on "Remove individual cookies" and type "doubleclick" into the "Search" bar.
Click on the Doubleclick cookie that appears, click "Remove Cookies," then click "Close" and "OK."