dblink_disconnect - Man Page

dblink_disconnect() returns text
dblink_disconnect(text connname) returns text

dblink_disconnect() closes a connection previously opened by dblink_connect(). The form with no arguments closes an unnamed connection.

connname

The name of a named connection to be closed.

Returns status, which is always OK (since any error causes the function to throw an error instead of returning).

SELECT dblink_disconnect();
 dblink_disconnect
-------------------
 OK
(1 row)

SELECT dblink_disconnect('myconn');
 dblink_disconnect
-------------------
 OK
(1 row)