To manage your Security Settings in Opera, do the following:

1. Go to Opera > Settings . The Settings window appears.
2. Click Privacy & security on the left navigation panel.
3. Click Manage certificates for an overview of your installed certificates. The Certificate Manager window appears. This window contains the following tabs:
4. You can view, delete, import or export any of these certificates. Then click OK.
5. To not allow any cookies on your computer, select the Block sites from setting any data and the Block third-party cookies and site data checkboxes.
   Note: For more information about cookies, see the Managing Browser Cookies how to article.