How to remove some external js files from source?

Question

I need to remove some external .js files from source here is source: view-source:buhehe.de/ausmalbilder/ There is 3 jquery library and I don't know what is difference, why is it not one enough?

<script type='text/javascript' src='http://buhehe.de/wp-includes/js/jquery/jquery.js?ver=1.12.4'></script>
<script type='text/javascript' src='http://buhehe.de/wp-includes/js/jquery/jquery-migrate.min.js?ver=1.4.1'></script>
<script type="text/javascript" src="http://buhehe.de/wp-content/themes/tema/js/jquery-3.2.1.min.js"></script>

Can I leave only one?

And how can I remove following:

<script type='text/javascript' src='http://buhehe.de/wp-content/themes/heatt/js/small-menu.js?ver=4.9.1'></script>
<script type='text/javascript' src='http://buhehe.de/wp-includes/js/wp-embed.min.js?ver=4.9.1'></script>

Answer 1

You can use wp_dequeue_script to achieve this assuming they are using wp_enqueue_script to add the scripts in the first place.

Learn more about enquene and dequeue: https://developer.wordpress.org/reference/functions/wp_enqueue_script/ https://codex.wordpress.org/Function_Reference/wp_dequeue_script

function dequeue_script() {
   wp_dequeue_script( 'http://buhehe.de/wp-content/themes/heatt/js/small-menu.js?ver=4.9.1' );
   wp_dequeue_script( 'http://buhehe.de/wp-includes/js/wp-embed.min.js?ver=4.9.1' );
}
add_action( 'wp_print_scripts', 'dequeue_script', 100 );

Answer 2

Firstly: Are you absolutely sure that you don't need them?

Secondly: I'm assuming small-menu.js is for the mobile menu and wp-embed.min.js you want in case you use embeds.
If I'm right, then you might want to keep the former. Aside from that you likely will find a wp_enqueue_script line for the former in your theme's functions.php. For the latter take a look at »What does wp-embed.min.js do in WordPress 4.4?«.
To keep it short and simple about the jQuery lines, WordPress loads jquery.js and jquery-migrate.min.js for compatibility reasons. I would suggest you keep it that way, unless you are really sure what you're doing.
Additionally your theme loads another jQuery source, which generally isn't recommended. But there might be a reason to do so, so it can't be easily answered, if you simply can remove it. You'll likely find this one it the functions.php as a wp_enqueue_script line too.