Default [Q] Help please with 'unroot'?

Hi all, I'm selling/trading my g2 which I rooted using iwo root so that I could change colours/status bar etc, I've just done a factory reset but when turning back on it popped with team win recovery project jargon like an old computer which doesn't look 'standard' is there a way I can remove this?

Please help a non techy guy!

I'm on a D802 in the uk on kitkat 4.4.2