function remove_noroleusers() {

    global $wpdb;

    $args = array( 'meta_key' => 'wp_capabilities','meta_value' => 'a:0:{}','meta_compare' => '=') ;

    $noroleusers = get_users( $args );

    if( !empty($noroleusers) ) {

        require_once( ABSPATH.'wp-admin/includes/user.php' );

        $i = 0;

        foreach( $noroleusers as $noroleuser ) {

            // if( wp_delete_user( $noroleuser->ID ) ) { $i++; }

        }

        echo $i.' Users deleted';

    } else {

        echo 'No Users deleted';

    }

}

remove_noroleusers();