@wtfrank Thank you! Really need to spend more time on JS

This is what I do, but doesn't seem to work

var thisRoom = Game.spwans["Spawn1"].room;
var constructionSites = thisRoom.find(FIND_CONSTRUCTION_SITES);
for (var site in constructionSites) {
  if (site.structureType == STRUCTURE_ROAD) {
     site.remove();
 }
}

From my debugging result, looks like site.structureType is undefined.