final public static function deleteOtpToken (string $username)
	{
		if ($username == $_SESSION['username']) {
			$tokenValue 				= NULL;
			$tokenTime 					= NULL;
			$_SESSION['otp_token'] 		= NULL;
			$_SESSION['otp_token_time'] = NULL;
		}
		return self::setUserOtpToken($username, $tokenValue);
	}