The PHP ftp_rmdir() function deletes a directory on the FTP server.

<?php
// connect and login to FTP server
$ftp_server = 'ftp.example.com';

$ftp_conn = ftp_connect($ftp_server) or die('Could not connect to ' . $ftp_server);
$login = ftp_login($ftp_conn, $ftp_username, $ftp_userpass);

$dir = 'php/';

// delete the directory
if (ftp_rmdir($ftp_conn, $dir)) {
    echo 'The directory was deleted successfully';
}
else {
    echo 'There was a problem deleting the directory';
}

// close connection
ftp_close($ftp_conn);
?>

// deletes the directory on the FTP server

ftp_rmdir(ftp_conn, dir)