Deleting code on child theme

Hi,

I need help deleting a code on my child theme. I don´t want the featured image to appear on top of my posts, as it´s set by default. On the parent theme, all I had to do was to delete this from post.php:

<?php if ( current_theme_supports( 'get-the-image' ) ) get_the_image( array( 'meta_key' => 'Thumbnail', 'size' => 'single-thumbnail', 'link_to_post' => false, 'image_class' => 'featured', 'attachment' => false ) ); ?>

On my child theme I only got the style.css. Should I create a post.php file? How do I do it… I created the style.css using a plugin. Also, once I create it, what should I add?

Thanks.

My site: http://www.practicaryoga.com