You can fully disable Groups by using the Uninstall Groups for Business option. This will make all of Groups' contents inaccessible to everyone, but the information will be kept and can be restored by reinstalling the service:
If you uninstall Groups and later wish to bring it back, take these steps from the administrator home:
- Select Apps
- Click on G Suite
- Click on ADD SERVICES
- Find Groups for Business in the Already Purchased Services section and click ADD IT NOW:
You can use these same steps to reinstall other G Suite services, and also to add more features in the Additional Paid Services and the Other Services sections.