How do I completely delete all history and data from Samsung Galaxy tablet? I want to sell my Samsung Galaxy tablet after getting a new iPad from work.  I've done the reboot / factory reset to erase my personal info and history, but my photos and contacts are still showing.  Is it possible to erase EVERYTHING in order to sell it? I don't want anyone being able to access my previous accounts or information.
Just goto your dial pad and enter *2767*3855# 
your device will then reset itself and erase all your personal informations and settings. 

This page will help you to do factory restore your Samsumg Galaxy Tab through Main menu as well as Hard key reset. 

http://galaxytablettalk.com/galaxy-tab-tutorials/how-to-reset-samsung-galaxy-tab-to-factory-settings