delete-other-windows is an interactive compiled Lisp function in `window.el'.

It is bound to C-x 1, <menu-bar> <file> <one-window>.

(delete-other-windows &optional WINDOW)

Make WINDOW fill its frame.
WINDOW must be a valid window and defaults to the selected one.
Return nil.

If the variable `ignore-window-parameters' is non-nil or the
`delete-other-windows' parameter of WINDOW equals t, do not
process any parameters of WINDOW. Otherwise, if the
`delete-other-windows' parameter of WINDOW specifies a function,
call that function with WINDOW as its sole argument and return
the value returned by that function.

Otherwise, if WINDOW is part of an atomic window, call this
function with the root of the atomic window as its argument. If
WINDOW is a non-side window, make WINDOW the only non-side window
on the frame. Side windows are not deleted. If WINDOW is a side
window signal an error.