Go into jmx-console, jboss.web:service=ModClusterService, invoke the "disable" operation. Node logs this in server.log:

009-03-16 17:15:58,765 ERROR [org.jboss.modcluster.mcmp.impl.DefaultMCMPHandler] (http-192.168.2.2-8080-2) Error [null: null:

{4}] sending command DUMP to proxy 192.168.2.3:6666, configuration will be reset
2009-03-16 17:16:55,250 ERROR [org.jboss.modcluster.mcmp.impl.DefaultMCMPHandler] (http-192.168.2.2-8080-2) Error [null: null: {4}

] sending command DISABLE-APP to proxy 192.168.2.3:6666, configuration will be reset