This tutorial might be good for you when developing your own module and you need to remove a child block in a page. By using layout update, you will not need to override HTML file. In this post, I will assume that you will need to remove a child block in product view page.
For example, you want to remove block media from product page. Here is xml in catalog.xml:
Now what you need is to have a XML file in your module to update that layout. Here is what you need: