Reference from: http://www.sevenforums/tutorials/88554-windows-update-enable-disable-access.html

This will allow you to enable or disable all users access to use all Windows Update features in Windows 7. The Windows Update features include installing updates, check for updates, change settings, view update history, and restore hidden updates.

It may be handy to set Windows Update settings the way want them, then disable access to prevent changes or unwanted updates from being manually installed by another user.

When disabled, you will see the Some settings are managed by your system administrator information message.

EXAMPLE: Windows Update Enabled and Disabled

1. To Enable Windows Update Access

A) Click on the Download button below to download the file below.

Enable_Windows_Update_Access.reg 

B) Go to step 4.

2. To Disable Windows Update Access with No Notifications
NOTE: This setting will remove all access to Windows Update features and no notifications will be shown.

A) Click on the Download button below to download the file below.

Disable_Windows_Update_Access_and_No_Notifications.reg 

B) Go to step 4.

3. To Disable Windows Update Access and Show Restart Notifications
NOTE: This setting will remove all access to Windows Update features, but will show notifications about restarts that are required to complete an installation.

A) Click on the Download button below to download the file below.

Disable_Windows_Anytime_Upgrade.reg

4. Click on Save, and save the .reg file to the desktop.

5. Right click the downloaded .reg file on the Desktop and click on Merge.

6. Click on Run, Yes, Yes, and OK when prompted.

7. When done, you can delete the downloaded .reg file if you like.

1. Open the  all users ,  specific users or groups , or  all users except administrators  Local Group Policy Editor for how you want this policy applied.

2. In the left pane, click on to expand User Configuration, Administrative Templates, Windows Components, andWindows Update. (see screenshot below)

 

3. In the right pane, right click on Remove access to use all Windows Update features and click on Edit. (see screenshot above)

4. To Enable Windows Update Access

A) Select (dot) either Not Configured or Disabled. (see screenshot below step 7)

B) Go to step 7.

5. To Disable Windows Update Access with No Notifications
NOTE: This setting will remove all access to Windows Update features and no notifications will be shown.

A) Select (dot) Enabled, then select 0 - Do not show any notifications under Options. (see screenshot below step 7)

B) Go to step 7.

6. To Disable Windows Update Access and Show Restart Notifications
NOTE: This setting will remove all access to Windows Update features, but will show notifications about restarts that are required to complete an installation.

A) Select (dot) Enabled, then select 1 - Show restart required notifications under Options. (see screenshot below step 7)

7. Click on OK. (see screenshot below)

8. Close the Local Group Policy Editor window.