Remove next and previous story

How do I remove next and previous story of the articles, or if I turn it on a couple of pages?

Go to article manager, click on options icon in top-right corner, go to articles tab , find:

Show Navigation

set to hide.

That if default setting, you can do per article because every article has that setting

How to turn off the black box of the article title?

Try to rename :

templates\hot_tennis\html\com_content\article\default.php

to _default.php

that will make article layout be Joomla default

Thank you.
One more thing. How to add a font RobotoCondensed Polish characters? The Original of these characters are included

www.google.com/fonts/specimen/Roboto+Condensed#charset

ŁĄŚĆŹÓŻĘ etc.

Add this line in head section of index.php of template:

use like this in css files:

font-family: 'Roboto Condensed', sans-serif;

You have explanation on:

www.google.com/fonts#UsePlace:use/Collection:Roboto+Condensed