Hi Paul, Once a group is archived you cannot access it anymore. However the data for that group still remains.
Currently our engineers will need to un-archive it for you if needed.
We do want to add the option to un-archive a group and this is currently in our engineering queue.
At the bottom of group listing page, is a link to the archived groups.
Only Admins can see this link.
You can also select to permanently delete a group from the group settings page.
Permanently deleted groups cannot be recovered.