The good news is this is a Pi. If needed the sd card can be flashed again. You do not need to worry about bricking the Pi; because you can't and it might be easier to start fresh than to try to clean it up.
When you first booted it was set up and all that needed to be done was enabling the radio so you could get into the router and move the eth0 over to a new interface named wan.
Then get fancy with IPV6.