How can I delete "fetched" images using the Admin API?

The default behavior of the delete_resources Admin API call is deleting images of type upload. To delete images of type "fetch", the type parameter should be set to fetch.

For example in PHP:

$api->delete_resources(
   array("http://upload.wikimedia.org/wikipedia/commons/4/49/2006-11-28Calendula08-05.jpg"), 
   array("type" => "fetch")
);

Source: https://cloudinary.com/documentation/admin_api#delete_resources