If you're using LEOdex, click the withdraw button on the site and withdraw the swap.hive to your main account and you can then use blocktrades or Binance swap your HIVE for BTC like you would normally

If you're using HIVE-Engine, you can buy swap.BTC with your Swap.HIVE and then pull the swap.BTC straight out of HIVE-engine to say your LUNO account for cashing out. I think that's the better option, less steps involved and fees