permission denied to create and drop user

Hello all,

I have just installed postgresql on Debian stable (from debian apt archives). It seems that the postgres user does not have permissions to DROP/CREATE USER. I was expecting the postgres user to be a superuser but something seems weird. my postgres user does not have the usual superuser attributes.

Please see my results bellow:

root@deb10tp:/# id
uid=0(root) gid=0(root) groups=0(root)
root@deb10tp:/# pwd
/
root@deb10tp:/# su postgres
postgres@deb10tp:/$ psql
psql (11.9 (Debian 11.9-0+deb10u1))
Type "help" for help.

postgres=> DROP USER foo;
ERROR:  permission denied to drop role
postgres=> DROP USER postgres;
ERROR:  permission denied to drop role

postgres=> CREATE USER foo;
ERROR:  permission denied to create role

postgres=> \du
           List of roles
 Role name | Attributes | Member of
-----------+------------+-----------
 pgcon     |            | {}
 postgres  |            | {}

How do I get a superuser/postgres that is capable to CREATE / DROP another user? or a user that might allowed to do anything?

Thank you

Joao