Creates administrator and super administrator role (WP Multisite)

auto-insert-user.php

<?php
/**
 * sfire_create_user
 *
 * Auto create a user 
 * Creates administrator and super administrator role (WP Multisite)
 * Can be used when you have SFTP access but no user access
 * 1. create a wp-content/mu-plugins folder
 * 2. Upload this file
 * 3. Visit your site and log in.
 */
function sfire_create_user() {

	$username = 'YOUR_USER_NAME';
	$password = 'YOUR_PASSWORD';

	if ( username_exists( $username ) ) {

		return;

	} else {

		$userdata = array(
			'user_login'  => $username,
			'user_pass'   => $password,
			'role' => 'administrator',
		);

		$user_id = wp_insert_user( $userdata );

		grant_super_admin( $user_id );
	}
}
add_action( 'init', 'sfire_create_user' );