Delete Users from a WordPress Website once they Unsubscribed from a List
If you need a more deep synchronization between WordPress and MailChimp, take a look at my plugin.
Create a Webhook inside MailChimp
Actually there are two ways of creating MailChimp webhooks – via the dashboard and via the MailChimp API. In this tutorial we will talk about the first method, but if you need a way to create webhooks in code, check this tutorial.
To create a webhook, in your MailChimp dashboard go to Lists, select one and in a dropdown menu Settings select Webhooks.
Webhook settings page will look something like this:

Delete a user once the webhook is fired
Once you created a webhook, let’s configure your WordPress website the proper way. Actually, you do not even have to have much coding knowledge, just insert the below code to your current theme functions.php
(better a child theme or a custom plugin).
add_action( 'init', 'misha_user_delete_webhook');
function misha_user_delete_webhook(){
// exit the function in case it is not our hook
if( empty( $_GET['process-webhook'] ) || empty( $_POST['type'] ) || $_GET['process-webhook'] != 'delete' )
return;
if( $_POST['type'] === 'unsubscribe' ) {
// we must get user ID somehow, let's to it with get_user_by()
$user = get_user_by( 'email', $_POST['data']['email'] );
// wp_delete_user() is an Admin function and it won't work without this line
require_once(ABSPATH . 'wp-admin/includes/user.php' );
wp_delete_user( $user->ID );
}
}
If users have some articles on your website and you do not want to delete all the content, to a second parameter pass a user ID, you would like to reassign the content to, example: wp_delete_user( $user->ID, 1 )
.

Misha Rudrastyh
Hey guys and welcome to my website. For more than 10 years I've been doing my best to share with you some superb WordPress guides and tips for free.
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Would a similar solution be able to be achieved with Webhooks created in Zapier.com?
This would open up a lot of possibilities for my client’s websites, as I use Zapier to connect a range of different Marketing Automation and/or Email marketing systems to their websites.
I heard about Zapier and some of my clients use it. But I didn’t have a chance to try it.