[CalendarServer-users] calendarserver, postgres and user administration (pgadmin?)

Hi, I´ve installed calendarserver 9.1a1 under debian stretch as docker container and everything is running. But now I´ve a few active user on the server and some non-active users have test data in their accounts and I want to clean up these account before they could start using this server. How could I clean up these accounts? My first thoughts are that I have to clean them in the database but I didn´t get pgadmin working with the server. I don´t have any knowledge about postgresql :(. How could I set up a postgresql user and allow my pgadmin server (not on the same machine as calendarserver) to grant access? Could anybody please give me some hints? Best wishes, Michael