Exclude authors IDs from WP_Query

I am using this code, trying to exclude specific authors from WP_Query, however the author IDs in the array are not being excluded. Any ideas please?

<?php $  args  = array('meta_query' => array(array('who' => 'authors')),array( 'author__not_in' => array(10, 3, 4)) );$  site_url = get_site_url();$  wp_user_query = new WP_User_Query($  args);$  authors = $  wp_user_query->get_results(); ?>