code: def delete_file(self, record, field, return_format='json', event=None):
          
          self._check_file_field(field)
          # Load up payload
          pl = self.__basepl(content='file', format=return_format)
          del pl['format']
          pl['returnFormat'] = return_format
          pl['action'] = 'delete'
          pl['record'] = record
          pl['field'] = field
          if event:
              pl['event'] = event
          return self._call_api(pl, 'del_file')[0]
docs: Delete a file from REDCap
  
          Notes
          -----
          There is no undo button to this.
  
          Parameters
          ----------
          record : str
              record ID
          field : str
              field name
          return_format : (``'json'``), ``'csv'``, ``'xml'``
              return format for error message
          event : str
              If longitudinal project, event to delete file from
  
          Returns
          -------
          response : dict, str
              response from REDCap after deleting file