Magento_Sales/adminhtml/web/order/create/scripts.js

var config = {
    config: {
        mixins: {
            'Magento_Sales/adminhtml/web/order/create/scripts.js': {
                'Magento_Sales/web/order/create/scripts-mixins.js': true
            }
        }
    }
};

Magento_Sales/web/order/create/scripts-mixins.js
define([
    "jquery",
    'Magento_Ui/js/modal/confirm',
    'Magento_Ui/js/modal/alert',
    "mage/translate",
    "prototype",
    "Magento_Catalog/catalog/product/composite/configure",
    'Magento_Ui/js/lib/view/utils/async'
], function(jQuery, confirm, alert){

   return AdminOrder.prototype = {
       setCustomerId : function(id){
            return false;
            this.customerId = id;
            this.loadArea('header', true);
            $(this.getAreaId('header')).callback = 'setCustomerAfter';
            $('back_order_top_button').hide();
            $('reset_order_top_button').show();
        }
   }
});