Cisco Systems OL-10984-01 ユーザーズマニュアル

When you delete a group, contacts in the group are also deleted. However, if the 
contact belongs to multiple groups, only the one instance is deleted. 

You cannot delete the General group. 

To delete groups, use any of the following methods:

Control-click a group name > Delete Group.

Choose Contacts > Delete Group > [choose a group to delete]. 

The Recent 
Communications or 
Search panes 

Select a contact or contacts. Then choose 
Contacts > Add Contact To > [group name]. 

Control-click a contact and choose Add Contact  
To, then choose a group. 

The roster 

Right-click a name and choose Add Contact To, then 
choose the name of group.