To delete the scheduled transaction completely go to Schedules, choose the scheduled transaction you want to delete and click Options - > Delete.
Please note that all transactions that were accepted before the date the scheduled transaction was deleted from Scheduled view will not be deleted from the Registry. By deleting scheduled transaction from Schedules you assure that you'll never see this transaction in the registry as the required some action.
If you deleting scheduled transaction from registry view you just delete this particular transaction but it will appears again according to the scheduled period.