turn off php mail require smtp/login for all mail server wide

I want to turn off php mail require smtp/login for all mail server wide in my centos 7 server... Usually I would do this by editing php.ini but I can not see this anywhere on the CWP php.ini file... I do not want php mail at all as wordpress sites are horrible for sending tons of spam from non updated installs. I need all users to use smtp with authentication.
Where do I kill the php mail on a CWP server?

you need to disable mail function for php in php.ini
disable_functions = mail

Hello,
So with that setting at every PHP.ini version the accounts could not send through php-mail. Only with SMTP settings. Am I right?

http://wiki.centos-webpanel.com/how-to-disable-dangerous-php-functions

Hello,
So with that setting at every PHP.ini version the accounts could not send through php-mail. Only with SMTP settings. Am I right?

Yes, they would be forced to use SMTP Authentication on their mail server.

So many thanks.