Deletes a group.
The deleteGroup() function returns a Promise that resolves to the deleted group after it has successfully been deleted.
Only site admins and group admins can delete their group. After the group is deleted, it is removed from both your site and the site's Dashboard.
Note: If the suppressAuth option is set to true, all permissions are overwritten, and all site members (including non-group members) can delete a group.
ID of group to delete.
Authorization options.