How to delete a group RosterEntry?

Hi

I can delete a RosterEntry with:

rosterObj.removeEntry( buddyInRoster)

But this command removes all entries from the roster. There should be a delete command for a group only!

Do i have to create my own message for that ?

This message deletes poen@jabber.org from the group Friends2:

<item jid="poen@jabber.org"

name=“poen”>Friends2