Save();
fileName = GetFilePath() + GetFileName();

DeleteRow(1001, Bottom);
SaveAs(fileName.replace(".csv", "_01.csv"));

Open(fileName);
DeleteRow(2001, Bottom);
DeleteRow(1, 1000);
SaveAs(fileName.replace(".csv", "_02.csv"));

Open(fileName);
DeleteRow(3001, Bottom);
DeleteRow(1, 2000);
SaveAs(fileName.replace(".csv", "_03.csv"));

Open(fileName);
DeleteRow(4001, Bottom);
DeleteRow(1, 3000);
SaveAs(fileName.replace(".csv", "_04.csv"));

Open(fileName);
DeleteRow(1, 4000);
SaveAs(fileName.replace(".csv", "_05.csv"));