The only way your command line should be appearing is if in your CL you call QCMD.
I am presuming you have a CL that does that and that program is setup with QSECOFR authority so you can do things without signing on as QSECOFR.
If that is the case, why do you need to hide the command line?
If I am misunderstanding you, please give us more information.
There are other things you can do, but before we give you other options, it would be better if you gave us the business case for what you are trying to accomplish and we can give you a specific answer,