DROP GROUP
Name
DROP GROUP -- remove a user group
Description
   DROP GROUP removes the specified group.  The    users in the group are not removed.   
Parameters
- name
       The name of an existing group.      
Notes
   It is unwise to drop a group that has any    granted permissions on objects.  Currently, this is not enforced,    but it is likely that future versions of    PostgreSQL will check for the error.   
Examples
   To drop a group:
DROP GROUP staff;   
Compatibility
   There is no DROP GROUP statement in the SQL standard.