code: protected void delete(ColumnFamilyHandle cfh, WriteOptions writeOptions, byte[] key)
              throws RocksDbException {
          if (readOnly) {
              throw new RocksDbException.ReadOnlyException("delete");
          }
          if (cfh == null) {
              throw new RocksDbException.ColumnFamilyNotExists();
          }
          try {
              rocksDb.delete(cfh, writeOptions != null ? writeOptions : this.writeOptions, key);
          } catch (Exception e) {
              throw e instanceof RocksDbException ? (RocksDbException) e : new RocksDbException(e);
          }
      }
docs: Deletes a key.
  
  @param cfh
  @param writeOptions
  @param key
  @throws RocksDBException