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In the Notification Groups view, click the Delete button on for the same row of the notification group you would like to delete. You will be prompted to confirm that you want to delete the group.
Click the Delete button in the prompt to confirm that you would like to delete the group, The delete option permanently removes the notification group and from any stream where notification is set to send the notifications to.
You are returned to the Notification Groups view with a banner indicating the successful deletion of the notification group.