dropuser — remove a PostgreSQL user account
dropuser [connection-option...] [option...] [username]
        dropuser removes an existing
        PostgreSQL user.
        Only superusers and users with the CREATEROLE privilege can
        remove PostgreSQL users. (To remove a
        superuser, you must yourself be a superuser.)
      
dropuser is a wrapper around the SQL command DROP ROLE. There is no effective difference between dropping users via this utility and via other methods for accessing the server.
dropuser accepts the following command-line arguments:
username
              Specifies the name of the PostgreSQL user to be removed.
              You will be prompted for a name if none is specified on the command
              line and the -i/--interactive option
              is used.
            
-e--echoEcho the commands that dropuser generates and sends to the server.
-i--interactivePrompt for confirmation before actually removing the user, and prompt for the user name if none is specified on the command line.
-V--versionPrint the dropuser version and exit.
--if-existsDo not throw an error if the user does not exist. A notice is issued in this case.
-?--helpShow help about dropuser command line arguments, and exit.
dropuser also accepts the following command-line arguments for connection parameters:
-h host--host=hostSpecifies the host name of the machine on which the server is running. If the value begins with a slash, it is used as the directory for the Unix domain socket.
-p port--port=portSpecifies the TCP port or local Unix domain socket file extension on which the server is listening for connections.
-U username--username=usernameUser name to connect as (not the user name to drop).
-w--no-password
              Never issue a password prompt. If the server requires
              password authentication and a password is not available by
              other means such as a .pgpass file, the
              connection attempt will fail. This option can be useful in
              batch jobs and scripts where no user is present to enter a
              password.
            
-W--passwordForce dropuser to prompt for a password before connecting to a database.
              This option is never essential, since
              dropuser will automatically prompt
              for a password if the server demands password authentication.
              However, dropuser will waste a
              connection attempt finding out that the server wants a password.
              In some cases it is worth typing -W to avoid the extra
              connection attempt.
            
PGHOSTPGPORTPGUSERDefault connection parameters
PG_COLOR
              Specifies whether to use color in diagnostic messages. Possible values
              are always, auto and
              never.
            
This utility, like most other PostgreSQL utilities, also uses the environment variables supported by libpq (see Section 33.14).
In case of difficulty, see DROP ROLE and psql for discussions of potential problems and error messages. The database server must be running at the targeted host. Also, any default connection settings and environment variables used by the libpq front-end library will apply.
        To remove user joe from the default database
        server:
      
$dropuser joe
        To remove user joe using the server on host
        eden, port 5000, with verification and a peek at the underlying
        command:
      
$dropuser -p 5000 -h eden -i -e joeRole "joe" will be permanently removed. Are you sure? (y/n)yDROP ROLE joe;