ftp_cdup(ftp_connection)

<?php
$conn = ftp_connect("ftp.testftp.com") or die("Could not connect");
ftp_login($conn,"admin","ert456");

//Outputs the current directory
echo "Dir: ".ftp_pwd($conn);
echo "<br />";
//Change to the images directory
ftp_chdir($conn,"images");
echo "Dir: ".ftp_pwd($conn);
echo "<br />";
//Change current directory to parent directory
ftp_cdup($conn);
echo "Dir: ".ftp_pwd($conn);

ftp_close($ftp_server);
?>

Dir: /
Dir: /images
Dir: /