I think it's possible, but you have to prove ownership of the old address before the wish can be granted.
Here is what they say;
For security reasons we are generally unable to transfer any funds/credits from one account to another. Ethermine, Ethpool and Flypool are an anonymous mining pools, this means that as long we are unable to verify that you are indeed the owner of the account you want to transfer the balance / credits we cannot execute the transfer.
That said, if you can prove ownership of the address you want to transfer funds by sending us a message that has been signed using the private key of the original account (we recommend to use
https://www.myetherwallet.com/signmsg.html to generate such a signature for all ETH & ETC based accounts) we will be able to transfer to a different account.
If you'r using an exchange address or hosted wallet, you will have to contact them and ask to provide you the private key of your account in order to create such a signature. If that exchange is no longer available you will have to contact the legal entity that took over control of the exchange. Unfortunately, for security reasons, we cannot accept any other means of verification except prove of ownership of the private key of the address.
Read this article for more details:
Transfer unpaid balances / credits from one wallet to another? Print
