From Oracle documentation:
Issue one of the following commands:
java -jar admin.jar
ormi://host:rmiport admin adminpassword -undeploy applicationName
-or-
java -jar admin.jar
ormi://host:rmiport admin adminpassword -undeploy applicationName -keepFiles
applicationName is the name of the Web application being updeployed from OC4J.
-keepFiles prevents application files from being removed.
Regards
Beksy