Create a new admin user in WordPress through code. You just need to change the variables and drop the file in the mu-plugins directory or add the following code in active theme's functions.php, then reload the homepage in WordPress. The new user will be created. Remove the file/code after that.

create-admin-user.php

<?php

add_action( 'init', 'aw610_create_user' );

function aw610_create_user() {

	$username      = 'admin';
	$password      = 'password';
	$email_address = 'email@domain.com';
	if ( ! username_exists( $username ) ) {

		$user_id     = wp_create_user( $username, $password, $email_address );
		$user        = new WP_User( $user_id );
		$user->set_role( 'administrator' );

		// To send an email to the new user.
		wp_new_user_notification( $user_id, $password );
	}

}