How can I disable page/frame in wpf?

Question

I'm trying to make authorisation page and don't know how to close it or switch to Main Window by clicking on a LogIn button.

Answer 1

please be more specific. if you say that you have a page, a frame and a main window than i assume that you have something like <window><frame><page /></frame></window>.
then i have the question what do you want to close? you cant go back to mainwindow because you are in mainwindow. you could just navigate to a new page after successful login. but with the information you provided i cannot tell what exactly you have build/ what exactly you want to archieve.