You can easily convert ethers for bitcoins on https://bity.com. Follow these simple steps to get started:
1- Login to your account, then click on the Buy/Sell tab.
2- Choose "Ether" and the amount you would like to convert into bitcoins.
3- On the next screen will appear our ETH address: Please send the correct amount to our address by copy-pasting it into your favorite Ethereum wallet (You can also scan the QR code on the right if you have a camera).
It is as simple as that!