Here's how to prevent new cookies from being installed and how to delete existing cookies. The exact procedure depends on which browser you are using.

• Internet Explorer 9.0+
• Internet Explorer 8.0+
• Internet Explorer 7.0+
• Firefox 2.0+, 3.0+, 4.0+
• Google Chrome
• Safari

Internet Explorer 9.0+

To prevent new cookies from being installed

• Go to Tools in the menu bar
• Click on Internet Options
• Click on the Privacy tab on top
• Move the slider up to the "Block all Cookies" button

To delete existing cookies

• Go to Tools in the menu bar
• Click on Internet Options
• Click on the General tab which should be under "Browsing History" and click "Delete"

Internet Explorer 8.0+

To prevent new cookies from being installed

• Go to Tools in the menu bar
• Click on Internet Options
• Click on the Privacy tab on top
• Click on "Sites"
• A new window should open called "Per Site Privacy Actions"
• Type in the URL of the site in the "Address of website" box and click on Block

To delete existing cookies

• Go to Tools in the menu bar
• Click on 'Internet Options'
• Click on the Privacy tab on top
• Click on "Sites"
• A new window should open called "Per Site Privacy Actions"
• Under the "Managed websites" box should be a list of all the websites you have visited
• To remove all cookies click on the "Remove all" button

Internet Explorer 7.0+

To prevent new cookies from being installed

• Go to Tools in the menu bar
• Click on Options
• Click on the Privacy tab on top
• Click on the Advanced button
• Select "Prompt" for both "First party cookies" and "Third Party Cookies"

To delete existing cookies

• Go to Tools in the menu bar
• Click on Options
• Click on the General tab on top
• In the "Browsing History" section, click on "Delete"
• Click on "Delete Cookies"

Firefox 2.0+, 3.0+, 4.0+

To prevent new cookies from being installed

• Go to Tools in the menu bar
• Click on Options
• Click on the Privacy tab
• Disable the box that says "Accept Cookies From sites"

To delete existing cookies

• Go to Tools in the menu bar
• Click on Options
• Click on the Privacy tab
• Click on "Clear Now"
• Select "Cookies"
• Click on "Clear Private Data Now"

Google Chrome

To prevent new cookies from being installed

• Click on the spanner icon in the top right of the browser
• Click on "Options"
• Click on "Under the Bonnet" (UK) / "Under the Hood" (US)
• Click on the "Content settings" button in the Privacy section
• Ensure that "Allow local data to be set" is selected
• Select "Block sites from setting any data"

To delete existing cookies

• Click on the spanner icon in the top right of the browser
• Click on "Options"
• Click on "Under the Bonnet" (UK) / "Under the Hood" (US)
• Click on the "Content settings" button in the Privacy section
• Click on the "Clear browsing data" button

Safari

To prevent new cookies from being installed and delete existing cookies

• Go to the Safari menu (icon in top right of browser) and select Preferences
• In the popup window that appears, select the Security icon (a padlock)
• Under "Accept Cookies", select the "Never" button

Information by courtesy of All About Cookies