[WordPress] Set Cookies in WordPress

1-set-cookies-in-wordpress.php

<?php

/* Assume all validation and verification of the username has been completed
 * and that the username is stored in the $username variable.
 *
 * Note also that the DAY_IN_SECONDS is a constant provided by WordPress
 * so we're setting the cookie for one week.
 */
setcookie( 'acme_username', $username, time() + ( 7 * DAY_IN_SECONDS ) );

2-delete-a-cookie.php

<?php

/* Unset the value of the cookie in the $_COOKIE array and then set the 
 * cookie's value to an empty value and set it to a timestamp in the past.
 * This expired the cookie.
 */
unset( $_COOKIE['acme_username'] );
setcookie( 'acme_username', '', time() - ( 60 * 60 ) );

// Redirect the user back to the WordPress Homepage.
wp_redirect( home_url(), 302 );
exit;