How do I clear numbers/data from my cell phone?

I am currently selling my LG Chocolate 3 on ebay, and I need to clear the phone numbers, pictures, etc. from my phone. Is there an easy way to do this?How do I clear numbers/data from my cell phone?
In your Settings and Tools, go to Phone Settings and down to Security. It'll ask you for a Lock Code. Unless you already chose one, it's the last four digits of your cell phone number. Once you get past that, there should be a setting that states RESTORE PHONE. It'll ask you for the Lock Code again, but will wipe all the data on your phone at once.