hide featured image

hi I would need to hide the featured image in the posts of the articles on my website http://www.ilredelweb.it/fabiopic as you can see from the url: https://www.ilredelweb.it/fabiopic/junganalysis/the-unbounded- intuition/

I tried with this quick css but it doesn’t work:
.single-post .blog-meta .small-preview {
display: none;
}

#top.blog .post-entry.single-small .entry-content img,
#top.blog .post-entry.single-small .entry-content .avia-iframe-wrap{
display: none !important;
}

can you help me please?
Thank you
Gianluca from Italy