|When you get a laptop that is second hand you are suppose to wipe it and reinstall Windows every thing else is hacking because (unless specified by previous owner or search warrant) you are NOT allowed to access their data.|
Ok, that said, if you want to do things the right and legal way and you either have the systems disk that came with the laptop or went out and purchases a new Windows Systems disk, then all you have to do is run the systems disk and chose to delete the partition when it asks.
If you really want to hack the system then Google Hacking Windows. There are 1000 ways to do it. I can think of 3 easy ones right off the top of my head but can not say them because of forum policy.