Add new WordPress user via FTP

functions.php

<?php
//REF http://www.wpbeginner.com/wp-tutorials/how-to-add-an-admin-user-in-wordpress-using-ftp/
function wpb_admin_account(){
  $user = 'Username';
  $pass = 'Password';
  $email = 'email@domain.com';
  if ( !username_exists( $user )  && !email_exists( $email ) ) {
    $user_id = wp_create_user( $user, $pass, $email );
    $user = new WP_User( $user_id );
    $user->set_role( 'administrator' );
  }
}
add_action('init','wpb_admin_account');