If my erc20 tokens gets a value, How can i convert my erc20 token to ETH?
You can use etherdelta.com to convert your token to ETH. All you need to do is to import your wallet in ether delta. Before you do it, make sure to keep your private key safe and don't share it to other. Etherdelta may need your private key to import your account to them. That's what I do to convert my token to ETH.
Since original Etherdelta has problems, I prefer to use
Forkdelta or
IDEX. But to a great pity - there are no high volumes because these exchanges were created recently.