You can do it through hive-engine. Go to https://hive-engine.com/. Login with Hive Keychain. Then click "wallet" and click deposit. Select steem
You will get account name and memo. Send steem to this account with memo. After a while sell it on hive-engine. I did it a while ago and it works.
RE: Blocktrades no longer accepts Steem. How does one get money out of Steemit's on-site wallet now?