You can exchange your Steem Dollars on the Blocktrades market by right clicking in your wallet on your Steem Dollars. Choose sell. Blocktrades will open and you can select the coin of your choice. I suggest Litecoin over BitCoin but that depends where you want to send it. Then you need a wallet at CoinBase or any other service where you can get Dollars or your currency of choice. There you can initiate a bank transfer. It is all a bit long but worth it. Best idea is to get one of the many debit cards that work with BitCoin.