There are following steps for prevent right click windows using GPEDIT.
Step-1: First of all open Group Policy Editor using RUN Menu. Open RUN menu and Type "gpedit.msc".
Step-2: Click on "User Configuration-> Administrative Templates-> Windows Components-> Windows Explorer.
Step-3: Double Click on "Remove Windows Explorer's default context Menu"
Step-4: Click on "Enable" button and then click on "Apply" and "OK' button.
Now You can check.
Note: If You will want to more information, Please mail me on "info@itsolution4u.in"