In your main app file, find "InitInstance".
There, find a place where it says somomething like:
CMultiDocTemplate* pDocTemplate;
pDocTemplate = new CMultiDocTemplate(IDR_MyTYPE,
RUNTIME_CLASS(CMyDoc),
RUNTIME_CLASS(CChildFrame),
RUNTIME_CLASS(CMyView));
if (!pDocTemplate)
return FALSE;
AddDocTemplate(pDocTemplate);
Comment that not to create a default tab.
Hope it helps.