code: public static synchronized void removeTruncationRecord(UUID cfId)
      {
          String req = "DELETE truncated_at[?] from system.%s WHERE key = '%s'";
          executeInternal(String.format(req, LOCAL_CF, LOCAL_KEY), cfId);
          truncationRecords = null;
          forceBlockingFlush(LOCAL_CF);
      }
docs: This method is used to remove information about truncation time for specified column family