How to enable and disable the expose_php directive?

When the expose_php directive is enabled, PHP includes the following line in 
the HTTP response header when a PHP page is requested 
(the exact version number may differ depending on your configuration):

X-Powered-By: PHP/5.3.27

By default, the expose_php directive is enabled. However, you may not want to 
broadcast the specific PHP version your site is using. Similarly, 
some third-party applications require the expose_php directive to be disabled.

To disable the expose_php directive, use a text editor to modify your php.ini file as follows:

expose_php = off

With the expose_php directive disabled, PHP will not send the X-Powered-By header. 
To re-enable the expose_php directive and send the X-Powered-By header, 
modify your php.ini file as follows:

expose_php = on