There is no option to unarchive groups, only to "Delete Group". What can I do?
In the free plan you can only have 3 active groups, that's why your archived groups can't be unarchived. You already have 3 active groups in your account.
If you want to recover any archived group you will need to archive one of the active groups.
Hope this clears your doubts.
I archived all my groups but still couldn't unarchive any. That's why I made new groups.
Right now you have 3 active groups. If they are new you can remove them and if you want we can unarchive for you the 3 groups you want.