11th October 2018: PostgreSQL 11 RC 1 Released!
Unsupported versions: 7.0 / 6.5 / 6.4

Chapter 29. Adding and Deleting Users

createuser enables specific users to access Postgres. dropuser removes users and prevents them from accessing Postgres.

These commands only affect users with respect to Postgres; they have no effect on a user's other privileges or status with regards to the underlying operating system.