Where is the delete key on a mac book pro?

It depends what you want to do. On Macs, you have a forward delete (the delete you know from Windows) and a backwards delete (backspace). If you want to forward delete, you can press Fn + Back delete. If you want to, for example, delete a file, then you press CMD + Back delete, which skips any warning messages and sends it straight to the trash (handy sometimes).