Confirmed this works:

From http://answers.microsoft.com/en-us/windows/forum/windows_other-windows_update/shutdown-win-7-without-updates/c6c25dab-db0b-4539-bf16-74a2fdabc454

go to Start -> Run -> gpedit.msc -> User Configuration -> Administrative Templates -> Windows Components -> Windows Update.

There, you will find an option called “Do not adjust default option to ‘Install Updates And Shut Down’ in Shut Down Windows dialog box”. If you enable this, then clicking “Shut Down” will just shut down your computer without installing updates. However, the “Install Updates And Shut Down” option is still available in the little menu, in case you need it

I tested it by myselft and confirmed this works:

1. Go to Start
2. Run
3. gpedit.msc
4. User Configuration
5. Administrative Templates
6. Windows Components
7. Windows Update.

There, you will find an option called “Do not adjust default option to ‘Install Updates And Shut Down’ in Shut Down Windows dialog box”. If you enable this, then clicking “Shut Down” will just shut down your computer without installing updates. However, the “Install Updates And Shut Down” option is still available in the little menu, in case you need it