Remove the SIM card and the SD card first. Factory reset it again ensuring the internal user storage space is cleared as part of the reset. You should keep the SIM card. If you want to sell the SD card with the phone, also back it up to a computer if it contains information and reformat the SD card too. After the phone factory reset turn it off on the first "setup/activation screen".
I'm most definitely NOT a VZW employee. If a post answered your question, please mark it as the answer.