docs: def delete_offline_reports(self):
          """
          Delete all stored offline reports
          :return: List of reports that still require submission
          """
          reports = self.get_offline_reports()
          remaining_reports = reports[:]
          for report in reports:
              with open(report, 'r') as _f:
                  try:
                      js = json.load(_f)
                  except ValueError as e:
                      logging.error("%s. Deleting crash report.")
                      os.remove(report)
                      continue
                  if js['SMTP Submission'] in ('Sent', 'Disabled') and js['HQ Submission'] in ('Sent', 'Disabled'):
                      # Only delete the reports which have been sent or who's upload method is disabled.
                      remaining_reports.remove(report)
                      try:
                          os.remove(report)
                      except OSError as e:
                          logging.error(e)
  
          self.logger.info('CrashReporter: Deleting offline reports. %d reports remaining.' % len(remaining_reports))
          return remaining_reports