May I ask how you came to be in possession of Ehtereum in the first place? Because from my experience it is a tad bit harder to buy Ethereum that Bitcoin 
To exchange your ETH to BTC the best way is to register on some exchange where both ETH and BTC can be traded: Poloniex, Gdax, Coinbase, cex.io and many more.
To exchange your ETH to BTC the best way is to register on some exchange where both ETH and BTC can be traded: Poloniex, Gdax, Coinbase, cex.io and many more.
Even I had used this websites to convert the Ehtereum to Bitcoin.Even you can keep your ETH coins because in future even ETH value will increases and you will get some more Dollars from ETH itself.ETH was in second place ,so you will get some more profit from ETH itself.My suggestion is to HODL your ETH coins.