pert:
Yes, you can bend the shield pins that connect to Arduino pins 0 and 1 out so they don't go into the header and then use a jumper to connect them to any pins you like, even software serial if you change the baud rate but since you have a Mega hardware serial is the way to go.
If you're using the WiFiESP library, which I recommend despite the debug output thing, then you can pass it any object you like from your sketch to communicate with the ESP8266. So no modification of the library necessary, in your case you would only need to do:
I don't even need to do that pert.
I just turned the two dip switches to the off positions and it has the same effect as bending the pins out of the way.