code: def delete_den(self):
          '''
          Delete all denied keys
          '''
          keys = self.list_keys()
          for status, keys in six.iteritems(self.list_keys()):
              for key in keys[self.DEN]:
                  try:
                      os.remove(os.path.join(self.opts['pki_dir'], status, key))
                      eload = {'result': True,
                               'act': 'delete',
                               'id': key}
                      self.event.fire_event(eload,
                                            salt.utils.event.tagify(prefix='key'))
                  except (OSError, IOError):
                      pass
          self.check_minion_cache()
          return self.list_keys(f delete_den(self):
          '''
          Delete all denied keys
          '''
          keys = self.list_keys()
          for status, keys in six.iteritems(self.list_keys()):
              for key in keys[self.DEN]:
                  try:
                      os.remove(os.path.join(self.opts['pki_dir'], status, key))
                      eload = {'result': True,
                               'act': 'delete',
                               'id': key}
                      self.event.fire_event(eload,
                                            salt.utils.event.tagify(prefix='key'))
                  except (OSError, IOError):
                      pass
          self.check_minion_cache()
          return self.list_keys()
docs: Delete all denied keys