Hello

I am using Bittrex and am a bit clueless about how to sell off half of my MTL coin back to BTC and then from BTC buying a different coin.
In the wallet i do see both MTL and BTC and both have a plus and minus sign

When i click on the minus sign i need to enter the withdrawal address
When i click on the plus sign on BTC i do see the address but also a notice "Depositing tokens to this address other than BTC will result in your funds being lost."
So what if i transfer from MTL to BTC directly? it will all be lost because it is not a BTC ?
How else am i going to transfer then?

Thank you in advance