In the analytics report, when you try to delete a couple of segment groups and start over, an error is displayed when you delete Unable to delete: Group is used in a report or template.
To resolve the error, check the analytic report template. If the segment group is not associated with any template, click Create & Manage Report Templates in the Analytic Reports and expand the segment groups. If the segment group you want to delete is present, delete it and then check whether any reports are associated with the segment. If no reports are associated, then you can delete the segment group.