How to logout Miitomo account?

[faustine]

...without deleting the app?

 

[Leviathinian]

I don't know if it's a bit too late for answers, but I don't think there is a logout option.
I think the closest you get to doing it is to just close the app.
I think they didn't want multiple Miitomo accounts to be put on one device for some reason, and that's why.