Microsoft ha rilasciato una Knowledge base  dedicata ad aziende e ambienti Enterprise, allo scopo di istruire in dettaglio i passaggi da eseguire per bloccare l’aggiornamento di sistemi con Windows 7 e Windows 8/8.1 a Windows 10.

In ambienti Server con funzionalità WSUS, e senza l’aggiornamento 3035583, non ci sarà questo problema.

Per tutti gli altri riporto parziale contenuto:

You can manage the Windows 10 upgrade by using any of the following methods. 

Group Policy

Microsoft has released new updates to enable you to block upgrades to Windows 10 through Windows Update. These updates install a new Group Policy Object. Computers that have this Group Policy Object enabled will never detect, download, or install an upgrade to the latest version of Windows. 

To obtain and install these updates, go to the following Microsoft Knowledge Base articles: 

3065987 Windows Update Client for Windows 7 and Windows Server 2008 R2: July 2015

3065988 Windows Update Client for Windows 8.1 and Windows Server 2012 R2: July 2015

To configure this Group Policy Object by using Group Policy, the following conditions apply:

• The appropriate update must be installed.
• You must use the updated WindowsUpdate.admx file by copying the file from the editing policy location.

Computer Configuration

To block the upgrade by using Computer Configuration, follow these steps:

1. Click Computer Configuration.
2. Click Policies.
3. Click Administrative Templates.
4. Click Windows Components.
5. Click Windows Update.
6. Double-click Turn off the upgrade to the latest version of Windows through Windows Update.
7. Click Enable.

Policy path: Computer Configuration / Administrative Templates / Windows Components / Windows Update Policy
Setting: Turn off the upgrade to the latest version of Windows through Windows Update

Windows registry

Important Follow the steps in this section carefully. Serious problems might occur if you modify the registry incorrectly. Before you modify it, back up the registry for restoration in case problems occur.

To block the upgrade to Windows 10 through Windows Update, specify the following registry value:

Subkey: HKLMSOFTWAREPoliciesMicrosoftWindowsWindowsUpdate
DWORD value: DisableOSUpgrade = 1

Per ulteriori scenari, applicazioni ed istruzioni rimando direttamente alla KB in questione:

 How to manage Windows 10 notification and upgrade options