"Origin" Theme – Delete thumbnail on homepage

Hello, good afternoon.

I’ve recently switched over to the lovely looking ‘Origin’ theme, and I have a very small change that I want to make, but I can’t seem to find it out. I’ve searched the forums, and online, and the only answer I could find was to delete:

<?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 ) ); ?>

in the post.php in the Editor, but that didn’t do the trick.

On my homepage: IestynRoberts.com it shows a small thumbnail image next to the post, and then the big image next to that – is there a way to totally get rid of this thumbnail, and just keep the main image there? It happens to all the posts with images in them (that’s uploaded to my blog) – but I’ve not set them as featured images or anything.

Anyone got any suggestions as how to get rid of those wee thumbnails?
Thank you.