While Drupal has no way of disabling the rss-feeds by default, it is possible to override the rss-output, and tell Drupal to use another feed.
Create a new module with following code, and make sure to replace
function
unset($items['rss.xml']);
}
function
drupal_add_feed(url('feed/news', array('absolute' => TRUE)), 'Website News RSS');
// You can add as many feeds as you want.
}