Hi, in standart attributes I can change "Fill check" property for Owner to "No check". But it doesn't influe on behavior of system. I still can't create element without owner. Even for group.
For example I want to have hierarchy of bank accounts: group for banks or just My favorite bank accounts group, nevermind.

Valerii Diachenko,

unfortunately, this does not work, as well as any other tricks one can think of (such as assigning an EmptyRef() owner). The platform design implies that if a catalog has an owner, all its items have an owner.

Please tell me more about your task and I'll find another solution for you.

I can find another solution by myself. Use another catalog for grouping or add new attribute (Belongs to) for owner. It's not a problem. More difficult will be to configure lists or reports.
It's just a little confusing to be able to specify "No check" for "Fill check" and get error.