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())
{
  var page = doc.GetActivePage();
  page.PurgeUndo();
}