how do I clear my snow leopard before I sell it

Hello BRP,

It sounds like you are wanting to clear your personal info from your computer before you sell it. If you have completed the applicable steps in the article you came from, the next step is going to be to erase the hard drive to prepare it for re installation of the Operating System:

Mac OS X v10.6 Snow Leopard: How to Erase and Install

http://support.apple.com/kb/ht3910

Important: This procedure will completely erase your hard drive. If you have installed Microsoft Windows using Boot Camp, or have multiple partitions, this procedure will erase the partition you select.

Part One: Erasing the hard drive

1. Turn on the computer.
2. Insert the Mac OS X Install DVD into the optical drive, or insert the MacBook Air Software Reinstall Drive into the USB port.
3. Restart the computer.
4. Press and hold the "C" key while the computer starts up. The computer will start up using the Install media. Alternatively, press and hold the Option key at startup to select the volume containing the installer.
5. If your are using a wireless mouse, a mouse icon should appear asking you to turn the mouse on so that the computer can discover it.
6. Select a language, then press the right arrow key.
7. Click the Utilities menu, the choose Disk Utility.
8. Select a volume to erase (usually called Macintosh HD).
9. Click the Erase tab.
10. Click Erase... Important: This step will completely erase your hard drive. If you have installed Microsoft Windows using Boot Camp, or have multiple partitions, this procedure will erase the partition you select.
11. A dialog box appears asking if you want to erase the partition: click Erase.
12. After the partition is erased, choose Quit Disk Utility from the Disk Utility menu.

Thank you for using Apple Support Communities.

All the very best,

Sterling

Hello

What if I dont have the original disc? How do I do this?

Thanks

I Have Macbook 7.1, mid.2010. It came with snow leopard and later I have purchased Lion and Mountain Lion from AppStore. Now I have Yosemite.

DO I still need the original disc to clear my Macbook before selling it?

That is what you are supposed to do.

What to do before selling or giving away your Mac - Apple Support

Thank you it worked!

A Company I used to work for did HDD recover, and I am here to tell you that it is very easy to get every bit of information that the original user had written onto the drive. Our clients wanted files recovered and we were paid handsomely for it.

What you want is available for free and for a price. I would never trust a free application. But I would do one of two things, pay or destroy the drive. I choose Safewiper data wiper to erase my personal data on hard drive.

Source: http://www.safewiper.com/tutorials/how-to-wipe-mac-clean.html