How do I remove my wife's iCloud account and set up my own on her iPad?

Have followed You Tube videos ,have gone right back to factory settings .set it up for myself and it still comes back,welcoming my wife and all her details?

What am I doing wrong!

[Re-Titled by Moderator]

Original Title: Sirs,I wish to use my wifes iPad.I have set it back to factory settings I cannot delete the iCloud (although it states nothingis there so I continue to set up and it says Hello in my wifes name and more!!I am inmy eighties so need easy answers.