WINDOW must be a valid window and defaults to the selected one.
If the variable `ignore-window-parameters' is non-nil or the
`delete-window' parameter of WINDOW equals t, do not process any
parameters of WINDOW. Otherwise, if the `delete-window'
parameter of WINDOW specifies a function, call that function with
WINDOW as its sole argument and return the value returned by that
Otherwise, if WINDOW is part of an atomic window, call
`delete-window' with the root of the atomic window as its
argument. Signal an error if WINDOW is either the only window on
its frame, the last non-side window, or part of an atomic window that is its frame's root window.