Do a restore to factory settings. (ie, as a new device, not from a previous backup).
DO NOT SEND YOUR IPAD TO NIGERIA. DO NOT SEND YOUR IPAD TO NIGERIA. DO NOT SEND YOUR IPAD TO NIGERIA. DO NOT SEND YOUR IPAD TO NIGERIA. DO NOT SEND YOUR IPAD TO NIGERIA. DO NOT SEND YOUR IPAD TO NIGERIA. DO NOT SEND YOUR IPAD TO NIGERIA. DO NOT SEND YOUR IPAD TO NIGERIA.
I hope you get my point.
Why are you selling it anyway???