See the current Perl documentation for unlink.
Here is our local, out-dated (pre-5.6) version:
unlink - remove one link to a file
Deletes a list of files. Returns the number of files successfully deleted.
$cnt = unlink 'a', 'b', 'c'; unlink @goners; unlink <*.bak>;
Note: unlink() will not delete directories unless you are superuser and the -U flag is supplied to Perl. Even if these conditions are met, be warned that unlinking a directory can inflict damage on your filesystem. Use rmdir() instead.
LIST is omitted, uses