OpenAM Web Policy Agent Installation Guide
Chapter 7. Installing the Varnish Policy Agent

Shut down the Varnish server before you uninstall the policy agent.

$ sudo service varnish stop

To remove the web policy agent, use ./agentadmin.

$ cd /path/to/web_agents/varnish/bin/
$ ./agentadmin

Scroll down and select Remove 'agent' instance.