Compatibility with WooCommerce pre-order plugin

This plugin has compatibility issue with woocommerce pre-order plugin. When a pre-order product is added to the cart then the previous products should be removed from the cart. The reason is, woocommerce pre-order products should not purchased with normal products.

Can you at-least share instructions to build this feature. We can customize the existing plugin?

The page I need help with: [log in to see the link]