ftp_delete

<?php
$file = 'public_html/old.txt';

// set up basic connection
$ftp = ftp_connect($ftp_server);

// login with username and password
$login_result = ftp_login($ftp, $ftp_user_name, $ftp_user_pass);

// try to delete $file
if (ftp_delete($ftp, $file)) {
 echo "$file deleted successful\n";
} else {
 echo "could not delete $file\n";
}

// close the connection
ftp_close($ftp);
?>