Blocking cookies can be useful for many reasons, like protecting your privacy, changing the browser’s behavior when visiting certain websites, testing for web development, etc. To block a cookie you can click the button “Block cookie”. Afterwards you can choose on which parameters should the cookie be blocked.
For example if you leave the defaults “Block with domain” and “Block with name” enabled, all the cookies having both that domain and name will be automatically deleted upon creation. You can check and edit the list of blocked cookies by going in the extension’s options and clicking on “Blocked cookies” .