When working with Oracle middleware you will have to use the OC4JADMIN account at some point. As it is with all username password combinations it can happen that you forget this password. For example you lost it, can not remember it, you get a system that is installed by someone else and you do not have the password. The options why you do not have this password are endless..... reseting the password can be done however not via a simple command. You will need to undertake some steps. This is not a bad thing because in a normal situation you will have the password, however in cases you do not have it you can take the following steps:
1) Login to a shell account on your server (we do only explain UNIX/Linux installs) and go stop your middleware services with "opmnctl stopall".
2) Go to $ORACLE_HOME/j2ee/home/config and open the file system-jazn-data.xml with vi
3) Locate the XML User structure for oc4jadmin
4) Delete the data between the "credentials" tags and enter here a new password with a "!" in front if it. The exclamation mark is important to indeicat that this is the new password.
5) Go to $ORACLE_HOME/j2ee/oc4jinstance/persistence/ascontrol/ascontrol/securestore and delete all file's. This is the location where the cached password are saved so we have to delete them.
6) start your middelware again with a opmnctl command
You are done and ready to go with the new password.