Rename/Change Slug of a Plugin's Custom Post Type

// Change "portfolio" slug of "Portfolio" custom post type to "about"
function change_portfolio_post_types_slug( $args, $post_type ) {

   /*item post type slug*/
   if ( 'portfolio' === $post_type ) {
      $args['rewrite']['slug'] = 'about';
   }

   return $args;
}
add_filter( 'register_post_type_args', 'change_portfolio_post_types_slug', 10, 2 );