To disable the PHP processor in a given directory, put the following in an .htaccess file. If one doesn’t exist, create it.
# Disable PHP
AddHandler default-handler php
RemoveType application/x-httpd-php php
# Make .php files display as plain text
AddType text/plain php
This assumes an Apache server. PHP on IIS may involve different steps.
Files starting with a . are hidden by default on *nix OSes. To see them in listings, use ls -a.