Delete BOOKMARK-NAME from the bookmark list.
Removes only the first instance of a bookmark with that name. If
there are one or more other bookmarks with the same name, they will
not be deleted. Defaults to the "current" bookmark (that is, the
one most recently used in this file, if any).
Optional second arg BATCH means don't update the bookmark list buffer,
probably because we were called from there.
(fn BOOKMARK-NAME &optional BATCH)