A waypoint cannot be deleted by clicking and clicking a delete button.You have to find the waypoint in the route manually and then click on the corresponding waste bin.
At full zoom in you can only select an airport by clicking exactly in the middle. This is difficult to hit. Typically, you click on the runway at some point.
Sometimes a runway is automatically assigned, but most of the time it is not. I couldn't find out when a runway is assigned. It always chooses the east direction, no matter how the wind direction is configured.