Deactivate Windows 7 and go back to the trial period

1)Type cmd in Start menu.
2)Right-click on the first result (cmd.exe) and click on Run as administrator (confirm by clicking Yes if required).
3) Type in
Code: slmgr -upk
4) Type in
Code: slmgr -ipk D4F6K-QK3RD-TMVMJ-BBMRX-3MBMV