You can edit your contacts by right-clicking on them and selecting the appropriate option. This also works for groups.
Set as Favorite: Assigns the contact to your favourites section at the top of your Contacts list.
Add to Group: Adds a contact to a pre-existing group.
Remove from Group: Removes a contact from a group.
View Profile: Lets you view the contact’s contact card.
Edit Profile: Lets you edit the contact’s display name, personal phone numbers and conference bridge information.
Unsubscribe: Removes the presence relationship between you and the contact, so that you and the contact cannot see each other’s presence information. To re-establish the presence relationship, select Subscribe.
An unsubscribed contact remains on the contact list and is always shown without an availability flag.
Delete Contact: Removes the contact from your contact list.