If you have requested the creation of an email distribution group, hopefully you have also specified a group "Manager" for it. The Manager will be able to add and remove members from the group via Microsoft Outlook.
To add or remove group mambers:
1. Open the Outlook 'Address Book' in the menu ribbon.
2. Search the Global Address List for the group name, double-click it.
3. Select "Modify Members", and add/remove user names as needed.
(I DON'T THINK THIS WORKS ANYMORE, USERS WITH INFO ATTIRUBTE=QUERY VALUE WILL JUST GET RE-ADDED, VERIFY WITH NETVIGOUR)