I am aware that each user can create an Office 365 group by clicking the [+] icon which appears on the left side screen of OneDrive for Business. To prevent this, I carried out cmdlets to control from the Microsoft Planner, therefore Microsoft Teams also became unusable at the same time.

Then I have been changing the settings to activate Teams, however, each user is still able to create Office 365 groups from their own OneDrive for Business screen.
For the ease of management, I hope the feature will be implemented enables controlling to hide the [+] icon (to create the Office 365 groups) by settings as quickly as possible.