There's no such a thing about "unlearn" to day-dream, it's something that you need to control because you can lost in it. I'm taking medication for it actually (Bach Flowers) and it's really helping me because there's now way I could do it by my own.
I decide to ask for help when I started no knowing what the hell was doing here in real life, I mean, I have periods, or moments where I don't what the hell did while I was daydreaming so that thing started to freak me out.
I still day dreaming of course, I can't change that but I have a control right now.
Because there's a moment when you realized your life is happening only in your mind, and when you look at your real life, there's nothing there.
We need to spend the same time in both sides.