Stop displaying errors in production server in Drupal 7 How to stop Drupal from showing unnecessary errors?

I'm deploying my Drupal 7 site to production server, and I want to stop displaying general purpose errors.

EDIT:

I found something about showing errors in this link: 

&lt;?php
    error_reporting(-1);
    $conf['error_level'] = 2;
    ini_set('display_errors', TRUE);
    ini_set('display_startup_errors', TRUE);
?&gt;


Can someone explain what will be the appropriate value for $conf['error_level'] to stop displaying errors?
Did you try this way : admin/config/development/logging ?

(Where you can choose to display every messages, or just errors, or no message at all)