Windows 7 - Format disk

I am planning to sell my laptop so I need to clear any data remaining. One way is to format disk which uses dos but I can't get to C. I have c:\Users\ I've tried c:\ C\ c\cd etc but I can't get rid of Users and therefore I cannot use the F command. Now I am trying Darik's Boot ande Nute (dban) but I don't have an exe. file. I am also looking to revert to factory default - this requires a hint as to where this is using Control Panel. Program default is limited as far as I can see. I do not have any disks for eMachines G520.

Any help is appreciated
nof

Welcome
This may help restore to factory settings
How to Restore My eMachine to Factory Without a Disc | eHow.com

If you wipe the HD you'll not be able to run factory Recovery, which is on a partition unless it has been deleted or damaged. I would try to make the Recovery Disks first so you have a backup method.

If this fails, you'll need to call eMachine Tech support to order recovery disks, or find a Windows 7 installer for your version to clean reinstall with the Product Key on COA sticker.

Or you can go through the active User folders, Select All and delete all the files, then Uninstall programs as desired in Control Panel>Programs and Features. When it's done clean it up with CCleaner followed by Windows 7 defragger.

Just a few words to express my thanks for your taking the time to help me

nof