code: def deleteMultipleStoredSms(self, delFlag=4, memory=None):
          
          if 0 < delFlag <= 4:
              self._setSmsMemory(readDelete=memory)
              self.write('AT+CMGD=1,{0}'.format(delFlag))
          else:
              raise ValueError('"delFlag" must be in range [1,4]')
docs: Deletes all SMS messages that have the specified read status.
          
          The messages are read from the memory set by the "memory" parameter.
          The value of the "delFlag" paramater is the same as the "DelFlag" parameter of the +CMGD command:
          1: Delete All READ messages
          2: Delete All READ and SENT messages
          3: Delete All READ, SENT and UNSENT messages
          4: Delete All messages (this is the default)
   
          :param delFlag: Controls what type of messages to delete; see description above.
          :type delFlag: int
          :param memory: The memory type to delete from. If None, use the current default SMS read/delete memory
          :type memory: str or None
          :param delete: If True, delete returned messages from the device/SIM card
          :type delete: bool
          
          :raise ValueErrror: if "delFlag" is not in range [1,4]
          :raise CommandError: if unable to delete the stored messages