Windows 7 Network - Turn off "Display Password" prompt

That password is stored unencrypted, so no need to hide. I think you must be admin to see previously stored password in W7

See this link, about halfway down--I will copy what it says for your convenience. I have not tested this or used it so be cautious, as always, when adding to your GPOs
The method that I have used below is drastic as it prevents access to be able to edit WLAN profiles. Users can still connect to a wireless network they simply cannot edit any of the properties. Here’s how…
1.Create a new GPO and link it to the OU where you want the policy applied.
2.Edit the new GPO and navigate to User Configuration\Policies\Windows Settings\Security Settings\Software Restriction Policies.
3.In the Object Type pane, double click on “Enforcement” and change the “Apply Software Restriction Policies to the following:” and check “All Software Files” which will include DLL files.
4.Next go to the “Additional Rules” node, right click on the blank area and add a new path rule.
5.In the Path field type C:\Windows\System32\wlanui.dll and select the security level as Disallowed. wlanui.dll is the Wireless Lan User Interface GUI.
6.Go to Computer Configuration\Policies\Administrative Templates\System\Group Policy and set the “User Group Policy loopback processing mode” to Enabled and select Replace which will override any other policies this software policy will take precedence.

To lionelmm:

I like the looks of this, but:

If this rule is applied as a GPO, what happens when a new device (to be delivered to a new employee) must join the wireless network?

Would we be able to join without restriction or would we have to disable the GPO until the new device is joined.

Ultimately, the only .dll file that would be affected is wlanui.dll as shown is Step 5?

You can't disable this feature specifically. Rather, you have to disable access to "Network and Sharing Center" entirely for the users

http://superuser.com/questions/643886/keep-windows-from-showing-a-wifi-password

To disable Network & Sharing Center through GPO:

Create a new GPO and link it to the OU where you want the policy applied.

Edit the new GPO and navigate to User Configuration\Policies\Windows Settings\Security Settings\Software Restriction Policies.

In the Object Type pane, double click on “Enforcement” and change the “Apply Software Restriction Policies to the following:” and check “All Software Files” which will include DLL files.

Next go to the “Additional Rules” node, right click on the blank area and add a new path rule.
In the Path field type C:\Windows\System32\wlanui.dll and select the security level as Disallowed. wlanui.dll is the Wireless Lan User Interface GUI.

Go to Computer Configuration\Policies\Administrative Templates\System\Group Policy and set the “User Group Policy loopback processing mode” to Enabled and select Replace which will override any other policies this software policy will take precedence.

Note that it may still be possible to extract the password using other utilities:
http://securityxploded.com/wifi-password-secrets.php


You may also want to consider switching from a Pre-shared Key (PSK) for wifi to using a RADIUS server for authentication and encryption:
https://community.aerohive.com/aerohive/topics/why_would_i_want_to_set_up_my_wifi_network_with_a_radius_server

We have no problem connecting the device to the wireless network BEFORE connecting to the domain.  Out department touches all new devices for configuration before they're handed out to the end user.

Your solution should be just right for our needs.

Thanks!