I want that each user have the chance to deactivate his own voice mail.
Is it possible?. I use Unity 4.0.
I don't think that the user itself will be able to do this. You could just eliminate the Forward settings to VoiceMail but that can not be done from the CCMUser page (only CFwdALL), I guess that you could create an MLA user that will only have priviledge to change the phone settings in order to change the Forward rules in the CCMAdmin.
But at the end this is something that the Network Administrator should do not the final user itself.