iPhone "Restore" does not delete personal data! - Warning From CNET
When you're selling your old iPad, the first thing you must to do is delete all your personal data. Wipe everything from your iPad: photos, videos, apps, account info, passwords and other personal data stored on iPad.

Video Demo:
Code:
youtube.com/watch?v=wj_rS2dLfiM
Wondershare SafeEraser
iPhone Data Eraser, Wipe iPhone Remotely, Delete iPhone Data Before Selling; Works with all iOS Devices - Jailbroken iPhone friendly and also compatible with carrier-locked iPhones

Supported iOS Devices:

iPhone 5S, iPhone 5C, iPhone 5, iPhone 4S, iPhone 4
iPad Air, iPad mini, iPad with Retina Display, The new iPad, iPad 2, iPad 1
iPod touch 5, iPod touch 4