Force delete Group Site Collection after Group Deleted?

A few steps missing in this explanation

First you need to download and install the SP snap-ins for Powershell

https://www.microsoft.com/en-ie/download/details.aspx?id=35588

Then you can execute the SP commands in PowerShell. The next command must be run on the -admin site of your tenancy:

Connect-SPOService -url https://<yourtenancy>-admin.sharepoint.com/

 Then finally you can run the commands mentioned before for the deletion of the site:

Set-SPOSite -Identity https://<yourtenancy>.sharepoint.com/sites/<site> -LockState Unlock
Set-SPOSite -Identity https://<yourtenancy>.sharepoint.com/sites/<site> -owner <admin@domain.com>
Remove-SPOSite -Identity https://<yourtenancy>.sharepoint.com/sites/<site>

Hope this helps!

Here is what I noticed, though: This seems to be a problem when a group is created via Yammer and then pushed from Yammer into O365 as a group. At the time of this writing, O365 does not support creating an O365 groups that is then pushed into Yammer.