Trying to deque some .js from source

You could try using the script_loader_tag filter. If they are enqueued properly this should get rid of them based on the URLs you provide:

add_filter('script_loader_tag', 'custom_remove_scripts', 11, 2);
function custom_remove_scripts($link, $handle) {
    $urls = array(
         'http://buhehe.de/wp-content/themes/heatt/js/small-menu.js',
         'http://buhehe.de/wp-includes/js/wp-embed.min.js'
    );
    foreach ($urls as $url) {
        if (strstr($link, $url)) {$link = '';}
    }
    return $link;
}

Otherwise as already stated by others you would need to find where the links are hardcoded in your theme. If you find they are enqueued using wp_enqueue_script then you can remove them using wp_dequeue_script by their script handle not by their URL as in your code.

Try using wp_enqueue_scripts with the handle like this example in your functions.php file :

add_action( 'wp_enqueue_scripts', 'remove_scripts', 100 );
function remove_scripts() {

    wp_dequeue_script( 'original-handle' );
    wp_deregister_script( 'original-handle );

}

However, this will only work if they have been loaded correctly in using wp_enqueue_scripts. Looks like they have been hard coded in a file which isn't best practice in WordPress.