1. Delete the code that connects the snippet in the cart template:

<!-- Snippet for Simple Preorder app -->
{% include 'simple-preorder-bootstrap' %}

2. Delete the code that connects the snippet in the product template:

<!-- Snippet for Simple Preorder app -->
{% include 'simple-preorder-bootstrap' %}

3. Delete the snippet "simple-preorder-bootstrap.liquid".

If this does not work, please write to support@kad.systems