In order to remove the default privileges for any particular user/role, we should know the list of default privileges.
`psql` allows you to check default privileges via `\ddp` command (per database). You can start `psql` with `-E` switch that will show you internal queries used for displaying this information, or you can `\set ECHO_HIDDEN on` with the same effect.
Also, you can do `pg_dumpall -s | grep -E 'DEFAULT PRIVILEGE|\\connect' and it'll produce a list of all entries for all databases, along with database name.