Io ho trovato questo:
The software covered by this agreement is an upgrade to your existing operating system software, so the upgrade replaces the original software that you are upgrading. You do not retain any rights to the original software after you have upgraded and you may not continue to use it or transfer it in any way. This agreement governs your rights to use the upgrade software and replaces the agreement for the software from which you upgraded.
Rinunciare all'upgrade e tornare al sistema precedente rimane un opzione.