Eror while dropping a user

Hello,

Using PostgreSQL 9.6.9 on Linux amd64 platform.

I have two users that I cannot drop from the system. I revoked all
permissions from tables, sequences, functions. They do not own any objects.
My log lines are as following:
2018-08-03 23:24:03.897    There are 2 users that needs to be removed from
system.
2018-08-03 23:24:03.897    Removing user previliges on tables: pars.test
2018-08-03 23:24:03.899    Removing user previliges on sequences: pars.test
2018-08-03 23:24:03.900    Removing user previliges on functions: pars.test
2018-08-03 23:24:03.900    Dropping user itself: pars.test
2018-08-03 23:24:03.901    Drop user failed: SQL Error: ERROR:  role
"pars.test" cannot be dropped because some objects depend on it
AYRINTI:  1 object in database postgres
2018-08-03 23:24:03.901    Removing user previliges on tables: pars.test2
2018-08-03 23:24:03.902    Removing user previliges on sequences: pars.test2
2018-08-03 23:24:03.903    Removing user previliges on functions: pars.test2
2018-08-03 23:24:03.903    Dropping user itself: pars.test2
2018-08-03 23:24:03.904    Drop user failed: SQL Error: ERROR:  role
"pars.test2" cannot be dropped because some objects depend on it
AYRINTI:  1 object in database postgres

I could not find any reference on postgres database for these users. I am
not very good on database administration.

Any help is appreciated.

Thanks & regards,
Ertan