Content type drop down filter types
You can use Administer views but to quickly achieve this I would use the hook_form_alter. 

Do something like this, Although I would recommend you set this restriction to specific role but for this example I am going to ignore roles. Within hook_form_alter you do

if($form['#form_id] == 'node_admin_content') {
   unset($form['filter']['filters']['status']['filters']['type']['#options']['article']);
}


You can change the ['article'] to whatever the machine name of your content type is. use devel to find out what elements the $form variable contains.