Removing system user

[meimi]

Hello all,
  I have read some document about server hardening. It suggests me removing
the following users:
operator, games, news, uucp
and following groups:
operator, staff
  I can guess that games is used for playing and news is used for reading
news in news group. How about the other? Their descriptions in passwd are
not clear.
  Am I safe to remove them in normal server environment (web, mail, ftp,
DNS, SSH)?

Thanks
meimi
http://www.htmlcss.com