code: def delete_pid(self, force_del=False):
          
          pid = self.read_pid()
          if pid != getpid() or force_del:
              logger.debug('process %d tried to delete pid' % getpid())
              return False
  
          if access(self.pid_file_name, F_OK):
              try:
                  remove(self.pid_file_name)  # remove the old pid file
                  logger.debug('delete pid (%d)' % getpid())
              except:
                  logger.debug("can't delete pid file")
docs: delete the pid file