wordpress change post status to draft

gistfile1.txt

$posts = get_posts(array(
  'post_type' => $post_type,
  'posts_per_page' => -1,
  'post_status' => 'publish'

));

foreach ($posts as $post){
  $post->post_status = 'draft';

  echo wp_update_post($post);
  echo '<br/>';
}