docs: def delete(self):
          """Delete a registered DOI.
  
          If the PID is new then it's deleted only locally.
          Otherwise, also it's deleted also remotely.
  
          :returns: `True` if is deleted successfully.
          """
          try:
              if self.pid.is_new():
                  self.pid.delete()
              else:
                  self.pid.delete()
                  self.api.metadata_delete(self.pid.pid_value)
          except (DataCiteError, HttpError):
              logger.exception("Failed to delete in DataCite",
                               extra=dict(pid=self.pid))
              raise
          logger.info("Successfully deleted in DataCite",
                      extra=dict(pid=self.pid))
          return True