kollapsminoriteten/wp-content/plugins/post-thumb.php

<?php
/*
Plugin Name: Post Thumb Shit
Plugin URI:
Description: Remove that damn post-thumb!
Version:     1.0.0
Author URI:
Text Domain:
*/

/**
 * Remove annoying thumbnail from single posts.
 * @param $post
 * @return false|mixed
 */
function checkTheThumbnail($post)
{
    return is_single() ? false : $post;
}

add_filter('has_post_thumbnail', 'checkTheThumbnail');
add_filter( 'wp_prevent_unsupported_mime_type_uploads', '__return_false' );