Google Maps Polyline - How do I remove it?

Question

So I checked previous questions regarding this, which all relate to V2, which is of no help.

So, I create two markers, save them in an array as markers[\"to\"] and m

Answer 1

I don't see var before flightPath = new..., so I presume flightPath is a global variable.

function route(){
   //flightPath.setMap(null); Doesnt't work!?
   for(var key in markers) {
       flightPlanCoordinates.push(markers[key].position);
   }
   if(flightPath) {//If flightPath is already defined (already a polyline)
       flightPath.setPath(flightPlanCoordinates);
   } else {
       flightPath = new google.maps.Polyline({
           path: flightPlanCoordinates,
           strokeColor: "#FF0000",
           strokeOpacity: 1.0,
           strokeWeight: 2
      });
      flightPath.setMap(map);//It's not necessary to setMap every time
   }

}