First of all a tip on removing a Office 365 Group.
Remove-MsolGroup because it purges the group permanently. Always use
Remove-AzureADMSGroup to delete an O365 group.
Make sure you have Azure Active Directory PowerShell Version 2 installed else you will mis alot of cmdlets
To get all removed Office 365 Groups execute the command below
To get more details about the removed office 365 group execute the Get command included with the objectID of the removed group.
Get-AzureADMSDeletedGroup –Id <ObjectID>
How to restore your deleted Office 365 group
Once you have verified that the group is in soft deleted, the restore command will restore everything in the office group (it can take up to 2 days to restore everything)
Restore-AzureADMSDeletedDirectoryObject -Id <ObjectID>