var prj = DlxApp.GetJob().GetProject("Example Sch");
if (!prj.IsValid())
  prj = DlxApp.GetJob().NewProject("Example Sch");
var doc = prj.GetDocument("Examples Sch", DlxApp.DOCTYPE_SCHEMATIC);
if (!doc.IsValid())
{
  doc = prj.NewDocument("Examples Sch", DlxApp.DOCTYPE_SCHEMATIC);
  doc.SetPageFormat("A4", false);
}
if (doc.IsValid() && doc.Activate())
{
  var page = doc.GetActivePage();
  if (page.IsValid())
  {
    var layer = page.GetLayerFromType(DlxApp.LAYERTYPE_DRAWING);
    if (layer.IsValid())
    {
      // Erase all objects in the drawing.
      var sel = page.GetSelection();
      sel.SelectAll();
      sel.Delete();
    }
  }
}