public void TaBortAlumnKonto(object commandParameter) //Klar
{
Alumn.TaBort();
GLOBALSWPF.AktuellAlumn = null;
MainWindow loginWindow = new MainWindow();
foreach (var window in Application.Current.Windows)
{
if (window is MainAlumnWindow x)
{
x.Close();
}
}
loginWindow.Show();
}