Update policy-csp-windowssandbox.md

AllowProtectedClient will not be supported any time in the near future, and is not supported anywhere at the moment. This is residual from one of our interns adding it here in the doc, so it needs to be removed.

windows/client-management/mdm/policy-csp-windowssandbox.md

@@ -34,9 +34,6 @@ ms.date: 10/06/2020
   <dd>
     <a href="#windowssandbox-allowprinterredirection">WindowsSandbox/AllowPrinterRedirection</a>
   </dd>
-  <dd>
-    <a href="#windowssandbox-allowprotectedclient">WindowsSandbox/AllowProtectedClient</a>
-  </dd>
   <dd>
     <a href="#windowssandbox-allowvgpu">WindowsSandbox/AllowVGPU</a>
   </dd>
@@ -380,90 +377,6 @@ The following are the supported values:
 
 <hr/>
 
-<!--Policy-->
-<a href="" id="windowssandbox-allowprotectedclient"></a>**WindowsSandbox/AllowProtectedClient**  
-
-<!--SupportedSKUs-->
-<table>
-<tr>
-    <th>Windows Edition</th>
-    <th>Supported?</th>
-</tr>
-<tr>
-    <td>Home</td>
-    <td><img src="images/crossmark.png" alt="cross mark" /></td>
-</tr>
-<tr>
-    <td>Pro</td>
-    <td><img src="images/checkmark.png" alt="check mark" /><sup>9</sup></td>
-</tr>
-<tr>
-    <td>Business</td>
-    <td><img src="images/crossmark.png" alt="cross mark" /></td>
-</tr>
-<tr>
-    <td>Enterprise</td>
-    <td><img src="images/checkmark.png" alt="check mark" /><sup>9</sup></td>
-</tr>
-<tr>
-    <td>Education</td>
-    <td><img src="images/checkmark.png" alt="check mark" /><sup>9</sup></td>
-</tr>
-</table>
-
-<!--/SupportedSKUs-->
-<hr/>
-
-<!--Scope-->
-[Scope](./policy-configuration-service-provider.md#policy-scope):
-
-> [!div class = "checklist"]
-> * Device
-
-<hr/>
-
-<!--/Scope-->
-<!--Description-->
-This policy setting allows the IT admin to enabled increased-security settings on the Sandbox RDP session. These settings decrease the attack surface of the sandbox.
-
-> [!NOTE]
-> Enabling this setting may restrict user's ability to copy and paste files in and out of Windows Sandbox. 
-
-If this policy is not configured, end-users get the default behavior (Sandbox does not run in protected client mode). 
-
-If protected client mode is enabled, a user will not be able to disable protected client mode from their own configuration file. 
-
-If protected client mode is disabled, a user will be able to enable protected client mode from their own configuration file to make the device more secure. 
-
-> [!NOTE]
-> You must restart Windows Sandbox for any changes to this policy setting to take effect.
-
-<!--/Description-->
-<!--ADMXMapped-->
-ADMX Info: 
-- GP English Name: *Run Windows Sandbox in Protected Client Mode*
-- GP name: *AllowProtectedClient*
-- GP path: *Windows Components/Windows Sandbox*
-- GP ADMX file name: *WindowsSandbox.admx*
-
-<!--/ADMXMapped-->
-<!--SupportedValues-->
-The following are the supported values:
-
-- 0 (default) - Disabled
-- 1 - Enabled
-
-<!--/SupportedValues-->
-<!--Example-->
-
-<!--/Example-->
-<!--Validation-->
-
-<!--/Validation-->
-<!--/Policy-->
-
-<hr/>
-
 <!--Policy-->
 <a href="" id="windowssandbox-allowvgpu"></a>**WindowsSandbox/AllowVGPU**