For some reason, you might need to disable or uninstall APF firewall and replace with another firewall application. You might follow the steps as given below.
Basic step by step guide how to install and use APF firewall on your server.
service apf stop chkconfig apf off rm -rf /etc/apf rm -f /etc/cron.daily/fw rm -f /etc/init.d/apf
Done!!