Since you can't deposit Steem on Bittrex (or other exchanges) or sell it on Blocktrades the below work around will help you sell your Steem-
- Deposit your steem on steem-engine.com.
- Convert your steem to DEC.
- Go to Splinterlands.com and transfer in your DEC from Steem Engine
- Then Transfer out your DEC to Tron.
- Convert DEC to TRX on trontrade.io
- Send TRX to Bittrex