Step 1. Go to https://idex.market/balances

Step 2. On the right side of the page, click the WITHDRAW button for Ether

Step 3. Click "Withdraw entire balance" and then the WITHDRAW button.

Step 4. Click the CONFIRM button.

Step 5. Go back to https://idex.market/balances and make sure the Ethereum is in your wallet by checking the value under "My Wallet Balance". You might need to click the QUERY button to update the value.