How to Factory Reset Your Nexus 7 ?
Note: once RESET was performed, all data, apps, settings and personal information will be deleted after initialization.
Step1. Select the "Settings" option.
Step2. Select the "Backup & reset" from Setting menu.
Step3. Select "Factory data reset"
Step4. Touch the "Reset tablet" button.
Step5. Touch "Erase everything" to confirm.