groupdel - Delete a group
The groupdel command modifies the system account files, deleting all entries that refer to group. The named group must exist.
You must manually check all filesystems to insure that no files remain with the named group as the file group ID.
You may not remove the primary group of any existing user. You must remove the user before you remove the group.
/etc/group - group information
/etc/gshadow - secure group information
0 - success
2 - bad command syntax
6 - specified group doesn't exist
8 - can't remove user's primary group
10 - can't update group file