WordPress multisite plugin uninstall

uninstall.php

<?php

if ( !defined( 'WP_UNINSTALL_PLUGIN' ) ) 
	exit();

if ( is_multisite() ) {
  $blogs = $wpdb->get_results( "SELECT blog_id FROM $wpdb->blogs", ARRAY_A );
  if ( $blogs ) {
    foreach ( $blogs as $blog ) {
        switch_to_blog( $blog['blog_id'] );
            delete_option( 'plugin_option_name' );
        }
        restore_current_blog();
    }
} else {
        delete_option( 'plugin_option_name' );
}