-snip-
I don't think Bittrex has the option to sell/buy Bitcoin with USD right?
And IMO, it looks like OP is asking for a exchange where he is able to do exchanges between Bitcoin and real money, and not limited only to BTC/Altcoin tradings.
OP, unfortunally it's very hard to find an exchange that allows this kind of trades without requiring any ID verification because of the AML and KYC laws. In this case, it would be better if you try to do local P2P trades in the
Currency exchange board or maybe find a seller/buyer at
LocalBitcoins.