How to remove a class [closed]

by

The class WC_Checkout is assigned to a member of the class Woocommerce. So maybe something like this could work:

add_action( "plugins_loaded", "wpse_91273_custom_checkout", 999 );

function wpse_91273_custom_checkout()
{
    $GLOBALS['woocommerce']->checkout = new Custom_Checkout;
}