I haven't seen these adverts in file explorer in either my Win 10 tech preview PC (even though it's done a few updates over last week or so ) or the laptop with win 10 home on it, but there's plenty of guides to remove them, but their appearance seems random, may be
linked to machines that had the "free" upgrade from Win 7 or 8?
http://www.infoworld.com/article/317...-explorer.html
https://www.tenforums.com/tutorials/...dows-10-a.html
http://www.theverge.com/2017/3/9/148...-file-explorer