iPad upgrade

Tap on your account id in Settings > iTunes & App Store and log out of it, and then do Settings > General > Reset > Erase All Content And Settings - that should remove all of your content from the iPad and put it back to factory defaults

If I understand the question correctly, you are getting a new iPad and want to pass the old one to someone else?

On the old iPad, Open the Settings app > General > Reset (you will need to scroll down) > Erase All Content and Settings (and for good measure Reset All Setting, but probably isn't necessary).