You can set what new cookies can be installed and delete existing cookies in your browser.

The process varies from browser to browser.

Google Chrome

To prevent new cookies from being installed and delete existing cookies:

https://support.google.com/chrome/answer/95647?hl=en

Safari

To prevent new cookies from being installed and delete existing cookies:

http://help.apple.com/safari/mac/8.0/#/sfri11471

Internet Explorer

To prevent new cookies from being installed and delete existing cookies:

http://windows.microsoft.com/en-GB/internet-explorer/delete-manage-cookies

Firefox

To prevent new cookies from being installed:

https://support.mozilla.org/en-US/kb/enable-and-disable-cookies-website-preferences

To delete existing cookies:

https://support.mozilla.org/en-US/kb/delete-cookies-remove-info-websites-stored