So... a few things.
You need to know that a stash file is associated with a USER, and a ROLE.
You specify the name of the user on the command line when you run the Content Manager OnDemand arsstash command, and enter that user's password when prompted. But, the secret sauce is the -a parameter, which defines what role that user/password combination is for.
1 - Store the OnDemand userid and password (default)
2 - Delete the OnDemand userid and password
3 - Store the OnDemand userid and password for ARSLOAD
4 - Store the OnDemand userid and password for ODF
5 - Store the OnDemand userid and password for RDF
6 - Store the OnDemand userid and password for PDD
7 - Store the LDAP userid and password
8 - Store the DB2 userid and password
9 - Store the Oracle userid and password
So you need to get all three items correct - the User, the user's password, and the role you're assigning.
Also, it's not a good idea to create a CMOD stash file for the admin account. Someone who can read the stash file can use it to do anything they want (reset another user's passwords, delete data, etc.) It's better to create a user for a specific role, and assign the minimum access required (say, to work with a specific Application Group) to accomplish the task.
There's also a whole discussion to be had about arsdoc delete -- it's NOT wise to use that tool, since it calls into question the accuracy and completeness of your archive, and doesn't delete the underlying documents. If there are problems with your data, ask the team that supplied the data to correct their data quality issues, and then unload/reload.
Brice, can you give us more information on what you're trying to accomplish? Also, can you show us the command you used to create the OnDemand stash file, and how you're trying to use it?
-JD.