Withdraw H1 B Amendment after RFE response submitted

I am in India with approved H1B petition until 2019 with A location and got a requirement for B location and applied for H1B amendment. My attorney submitted RFE response to H1B amendment petition 2 days back in premium processing but the Client is informed suddenly that the position is closed now and asked to stop the process.

As already RFE responce is submitted what is the best way now to continue the petition or to withdraw the petition.

If we withdraw the amendment petition, is my first approved petition is valid to go for stamping ?