How to make a singular post type

Singular Post Type

add_action('admin_menu',  'hook_uniquePostTypes');
function hook_uniquePostTypes(){
  global $submenu, $menu;
  
  // post types to make singular
  $postTypes = array('example1', 'example2');
  
  foreach($submenu as $key=>$value){
    $name = preg_replace('/edit.php\?post_type\=/', '', $key);
    foreach($postTypes as $type){
      if ($type == $name){
        $uniquePost = get_posts(array('post_type' => $name));
        
        // this i worry about upon wordpress version changes
        unset($submenu[$key][5]); 
        if ($uniquePost){
          $submenu[$key][10][0] = preg_replace('/Add/', 'Edit', $submenu[$key][10][0]);
          $submenu[$key][10][2] = 'post.php?post=' . $uniquePost[0]->ID . '&action=edit';
        }
      }
    }
  }
  
}