Delete file named FILENAME. If it is a symlink, remove the symlink.
If file has multiple names, it continues to exist with the other names.
TRASH non-nil means to trash the file instead of deleting, provided
`delete-by-moving-to-trash' is non-nil.
When called interactively, TRASH is t if no prefix argument is given.
With a prefix argument, TRASH is nil.
(fn FILENAME &optional TRASH)