Sounds like they didn't wipe the TouchPad before selling it. You should peform a system erase so that you can start from the factory defaults, like you would if you bought the TouchPad new. To do this tap on the Launcher Arrow, tap on Settings tab, tap on Device Info, tap Reset Options, and finally tap Secure Full Erase. This ensures your TouchPad is reverted back to factory settings and the previous user's data has been securely wiped.
This process will eat your battery like crazy, so I recommend leaving the TouchPad connected to the wall charger. It could take 30 minutes or longer to complete.
When the TouchPad boots up after the Secure Full Erase, it will need to connect to your WiFi and it will ask you to sign in with an HP webOS Account. If you have one, sign in with it. If you don't have one, you can create it then.
