code: def remove_cache_tier(self, cache_pool):
          
          # read-only is easy, writeback is much harder
          mode = get_cache_mode(self.service, cache_pool)
          if mode == 'readonly':
              check_call(['ceph', '--id', self.service, 'osd', 'tier', 'cache-mode', cache_pool, 'none'])
              check_call(['ceph', '--id', self.service, 'osd', 'tier', 'remove', self.name, cache_pool])
  
          elif mode == 'writeback':
              pool_forward_cmd = ['ceph', '--id', self.service, 'osd', 'tier',
                                  'cache-mode', cache_pool, 'forward']
              if cmp_pkgrevno('ceph-common', '10.1') >= 0:
                  # Jewel added a mandatory flag
                  pool_forward_cmd.append('--yes-i-really-mean-it')
  
              check_call(pool_forward_cmd)
              # Flush the cache and wait for it to return
              check_call(['rados', '--id', self.service, '-p', cache_pool, 'cache-flush-evict-all'])
              check_call(['ceph', '--id', self.service, 'osd', 'tier', 'remove-overlay', self.name])
              check_call(['ceph', '--id', self.service, 'osd', 'tier', 'remove', self.name, cache_pool])
docs: Removes a cache tier from Ceph.  Flushes all dirty objects from writeback pools and waits for that to complete.
          :param cache_pool: six.string_types.  The cache tier pool name to remove.
          :return: None