I am not sure whether its possible to "disable" the close window in WPF. But you can hide the title bar which shows the minimize, maximize and close button by setting
WindowStyle
to
None
.
Do this in your XAML:
<Window x:Class="Window1"
WindowStyle="None"
Or you can create a custom title bar and create your own buttons for minimize, maximize and similarly for the close button(which you can disable it).
Good luck.