How to disable directory browsing in apache/httpd

find  the main apache’s config file httpd.conf is located.

If you use Debian, it should be here: /etc/apache/httpd.conf.
 Using file editor such as vim or nano open the file and find the line following:

Options Includes Indexes FollowSymLinks MultiViews

remove "Indexes" will be like follows:

Options Includes FollowSymLinks MultiViews

dont forget to restart apache