Cisco ASA 5505 combined with Draytek Vigor pro 5500

Hi,

I want to configure a Cisco ASA 5505 for client access to use RDP connections within a SSL tunnel.
But I allready got a router/firewall up and running in the LAN (Draytek Vigor pro 5500), which is working fine! So, I want to keep this one! So, I don’t want to use the firewall on the ASA. Is there a possibility to disable the firewall?

So I want to access the cisco ASA from the outside with a public IP address, which I translate in the NAT table of the Vigor PRO to the inside IP of the cisco ASA.

Is this possible??