I can not drop a user/role because an object depent on it.

Dear my friends....

I can not drop a user because another object need it. How can I know
which object need it? I really want to drop everything inside my
PostgreSQL, to reset my installation really from beginning.

postgres=# drop user ivia;
FEHLER:  kann Rolle »ivia« nicht löschen, weil andere Objekte davon
abhängen DETAIL:  Eigentümer von Datenbank iVia
7 Objekte in Datenbank iVia-->mytranslation: Error: can not delete Role
»ivia«, because another object depend on it DETAIL: owner of Database
iVia.
postgres=#

I've dropped the database iVia.

Thank you very much in advance.