You can withdraw your coins/tokens from dfinance back to the chain from which these coins/tokens arrived.
To withdraw your coins/tokens from PegZone you need to send only one transaction with dncli:
dncli tx currencies destroy-currency [chainID] [symbol] [amount] [recipient] [flags]
In the case of Ethereum, chainID will be ETH, and symbol also ETH, recipient is your address in Ethereum network (e.g. 0x01849...).