Go to the Azure AD Portal, https://portal.azure.com go to Azure Active Directory and navigate into Groups.
Click on the Group you want to remove and click “Delete”.
Note: This will soft delete the group so you will be able to restore it in the future (in case you regret it). But if you want to add it again (purging all the information, in an educational environment for a new scholar year for example) you’d need to purge them from the recycle bin.
To do this you can go and run the following only once per computer:
Open Powershell as administrator and run:
And accept the change, next, install the Powershell Module AzureAD.
Now, these commands you need to run them every time:
Connect to Azure AD
And finally, Remove the DeletedGroups:
Get-AzureADMSDeletedGroup | Remove-AzureADMSDeletedDirectoryObject