Hi F A,
thanks for your reply. It does not help. You have to keep in mind that my concept is about a folder where users are allowed to create new reports and dashboards. As owner of these objects, they're automatically admins for them. Even with their groups set to "DENY" for set permissions, they are still able to change the permissions on all objects they have created. That is the issue here.
And the users don’t tell me when they create new objects so I can change the owner to another (technical) user. I want a built-in solution that works or every new object instantly.