SQL

postgres set user as superuser

ALTER USER myuser WITH SUPERUSER;

postgres add superuser to database

create USER <<username>>;
ALTER USER <<username>> WITH SUPERUSER;
ALTER USER <<username>> WITH PASSWORD '<<password>>';

postgres create user with superuser privileges

sudo -u postgres createuser -s -i -d -r -l -w <<username>>
sudo -u postgres psql -c "ALTER ROLE <<username>> WITH PASSWORD '<<password>>';"