For PHP < 5.3 use:
$upOne = realpath(dirname(__FILE__) . '/..');
In PHP 5.3 to 5.6 use:
$upOne = realpath(__DIR__ . '/..');
In PHP >= 7.0 use:
$upOne = dirname(__DIR__, 1);
// One level up
echo str_replace(realpath(dirname(__FILE__) . '/..'), '', realpath(dirname(__FILE__)));
// Two levels etc.
echo str_replace(realpath(dirname(__FILE__) . '/../..'), '', realpath(dirname(__FILE__)));
dirname(__DIR__,level);
dirname(__DIR__,1);