I don't think so you need proxy server. The simple way to disable it by typing following at a shell prompt:
Code:
a2dismod proxy
/etc/init.d/apache2 force-reload
Many modules are installed by default and not required at all. It appears that your server acting as open proxy. If there is any problem, you can simply turn it on again by typing following two command:
Code:
a2enmod proxy
/etc/init.d/apache2 force-reload
access.log and error.log are important files to find out all errors / warning.