Q: how to restore to factory settings on OS X 10.6.8

Create a new user account with admin status. Log out of her old account and into the new account. Delete her old account.

This is all done via Accounts preferences.

Take a look at this link, http://support.apple.com/kb/HT3910?viewlocale=en_US

BTW, I would at least purchase a Snow Leopard DVD:

You can purchase Snow Leopard through the Apple Store: Mac OS X 10.6 Snow Leopard - Apple Store (U.S.). The price is $19.99 plus tax. You will be sent physical media by mail after placing your order.

After you install Snow Leopard you will have to download and install the Mac OS X 10.6.8 Update Combo v1.1 to update Snow Leopard to 10.6.8 and give you access to the App Store. Access to the App Store enables you to download Mountain Lion if your computer meets the requirements.

Apple Store Customer Service at 1-800-676-2775 or visit online Help for more information.

To contact product and tech support: Apple - Support - Contact Apple Support.