Global administration of groups
One of the benefits of groups is that users self-organize and self-manage. But occasionally the global administrator needs to view, create, and delete groups, and add or remove group administrators or members. The group dashboard in the Office 365 admin center is the place to do this, and as the global administrator, you don’t have to be a group member.
Groups global administration
A group administrator can also disable group creation by using Windows PowerShell to update the mailbox policy and remove the ability to create groups. Because OWA policies are per user, you can even limit the ability to create groups for some users and not others.
In a computer with an Internet connection, open PowerShell, copy and paste the following:
$O365Cred = Get-Credential
$O365Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://ps.outlook.com/powershell -Credential $O365Cred -Authentication Basic -AllowRedirection
Enter your Office 365 credentials when prompted.
Open Command Prompt, type the following command below and press Enter:
Set-OwaMailboxPolicy -Identity OwaMailboxPolicy-Default -GroupCreationEnabled $false