Log out not working with Log me in automatically

Originally Said By: Jason Byrnes

  that would defeat the purpose of having the autologin option on your site, just remove the auto login option if you don't want them to be automatically logged in.  

Hi Jason,
I have rest the cookies on the log out pages, which were set on the login page to a minus time period to achieve what the client requires.

The client will be using one PC between three staff on a two day per week sift system and the staff have to log out of their account after their two day sift before the next staff comes in to work.

I have used the following code to reset the cookies it seems to work is this correct?

<?php
if ("" == "") {
setcookie("RememberMePWD", "", time()-(60*60*24*30), "/", "", 0);
}
?>
<?php
if ("" == "") {
setcookie("RememberMeUN", "", time()-(60*60*24*30), "/", "", 0);
}
?>
<?php
if ("" == "") {
setcookie("RememberMePWD", "", time()-(60*60*24*30), "/", "", 0);
}
?>
<?php
if ("" == "") {
setcookie("RememberMeUN", "", time()-(60*60*24*30), "/", "", 0);
}
?>
<?php
if ("" == "") {
setcookie("AutoLoginPWD", "", time()-(60*60*24*30), "/", "", 0);
}
?>
<?php
if ("" == "") {
setcookie("AutoLoginUN", "", time()-(60*60*24*30), "/", "", 0);
}
?>
<?php
if ("" == "") {
setcookie("AutoLoginPWD", "", time()-(60*60*24*30), "/", "", 0);
}
?>
<?php
if ("" == "") {
setcookie("AutoLoginUN", "", time()-(60*60*24*30), "/", "", 0);
}
?>


Thanks