On Admin Mode, go to Start and search for "regedit" and Open Registry Editor.
Go to Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Policies
Right Click "Policies" and Create a new Key named "Google"
Once "Google" has been created, create another new key named "Chrome"
Go to the Chrome folder (Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Google\Chrome)
On the right side, right click and Create a "DWORD (32 bit value)
Once it has been created, right click on it and click "Modify".
Set the the Value Data to "2" and click ok
Right Click on the Created DWORD again and rename it to "IncognitoModeAvailability"
Check these entries and it should look like this when you're done.
Restart the PC.