How to remove leading pictures on post page

Hi all,

I have a problem with leading image on category pages. If post has some picture added from media, after publishing, there is part of this picture before every post on category page. I try to change featured image, bit it only affects slider.
How to remove this embarrassing cropped image?

Example: https://zupaluznica.org.rs/category/%D1%80%D0%B0%D0%B4%D0%BE%D0%B2%D0%B8/

Thanks
Miroslav