Remove a UI component child via Layout XML
We can read the document here: http://devdocs.magento.com/guides/v2.0/howdoi/checkout/checkout_customize.html. In your case: we can apply this guide:
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
layout="1column" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
<body>
<referenceBlock name="checkout.root">
<arguments>
<argument name="jsLayout" xsi:type="array">
<item name="components" xsi:type="array">
<item name="checkout" xsi:type="array">
<item name="children" xsi:type="array">
<item name="sidebar" xsi:type="array">
<item name="children" xsi:type="array">
<item name="summary" xsi:type="array">
<item name="children" xsi:type="array">
<item name="totals" xsi:type="array">
<item name="children" xsi:type="array">
<!--Remove fields-->
<item name="subtotal" xsi:type="array">
<item name="config" xsi:type="array">
<item name="componentDisabled" xsi:type="boolean">true</item>
</item>
</item>
<item name="shipping" xsi:type="array">
<item name="config" xsi:type="array">
<item name="componentDisabled" xsi:type="boolean">true</item>
</item>
</item>
<item name="grand-total" xsi:type="array">
<item name="config" xsi:type="array">
<item name="componentDisabled" xsi:type="boolean">true</item>
</item>
</item>
</item>
</item>
</item>
</item>
</item>
</item>
</item>
</item>
</item>
</argument>
</arguments>
</referenceBlock>
</body>
</page>
The result:
Read more here: http://devdocs.magento.com/guides/v2.1/howdoi/checkout/checkout_customize.html#disable-a-component
[EDIT]
Disable sidebar (Order summary) at checkout page.
<?xml version="1.0"?>
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" layout="checkout"
xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
<body>
<referenceBlock name="checkout.root">
<arguments>
<argument name="jsLayout" xsi:type="array">
<item name="components" xsi:type="array">
<item name="checkout" xsi:type="array">
<item name="children" xsi:type="array">
<item name="sidebar" xsi:type="array">
<item name="config" xsi:type="array">
<item name="componentDisabled" xsi:type="boolean">true</item>
</item>
</item>
</item>
</item>
</item>
</argument>
</arguments>
</referenceBlock>
</body>
</page>
