Elimnare/disabilitare pulsanti su barra menù form

private void MainForm_FormClosing(object sender,
FormClosingEventArgs e)
{
 //Annullo la chiusura solo se chiamata dall'utente
 if (e.CloseReason == CloseReason.UserClosing)
 {
  e.Cancel = false;
 }
}

Private Sub MainForm_FormClosing(ByVal sender As System.Object, _
ByVal e As System.Windows.Forms.FormClosingEventArgs) _
Handles MyBase.FormClosing
 If e.CloseReason = CloseReason.UserClosing Then
  e.Cancel = True
 End If
End Sub