You can stop the Proxy Server on Windows in any of the following ways:
On the Start menu, select Programs ⇒ Oracle Corporation ⇒ Oracle iPlanet Proxy Server4 ⇒ Stop Proxy Server
From a command prompt, go to server-root\proxy-serverid and type stopsvr.bat to stop the Proxy Server.
Use the Oracle iPlanet Proxy Server4 (proxy-serverid) service in the Services window: Control Panel ⇒ Administrative Tools ⇒ Services