​@giovanna.orlando 

This requires CSS. Its just one line but note that it will hide it from all details. 
.course__detail__asset {display:none;}

If you want to hide videos instead of the images you need to use a different target

.course__detail__video {display:none;}

Code:
.course__detail__asset {display:none;}
.course__detail__video {display:none;}

Alternative:

Lastly if you are trying to do it only on one content item you can use a HTML widget in the detail page sidebar and add the <style> tag. 

<style>
.course__detail__asset {display:none;}
.course__detail__video {display:none;}
</style>

​@giovanna.orlando Or just don’t upload a catalog or details page image at all.  Or go to layouts > details page and remove the placeholder for it.  Hope this helps.

​@Philcahill87 thanks so much! This works great for what I want.

Charles, thanks for your suggestion too, but I want to keep the images in the catalog, and just hide them on the course detail page. We customize many of our course detail pages, so want a solution that just takes care of them all at once instead of having to configure each one separately.

​@giovanna.orlando  You want this right ?  This has a detail and catalog image but the change is global and here is the CSS. ​@Philcahill87 I just noticed your answer and it is not the same as mine.  Is mine incorrect?

imgcsrcset*="cloudfront.net/thoughtindustries"] {
  display: none;
}

Phil’s answer is working for me so I’m sticking with it, but thanks again Charles.

We ended up going with shrinking the thumbnail instead, to a 30% width. And then for small screens, left it at 100%. Sharing here in case anyone else wants to do something similar. Thanks again ​@Philcahill87 for getting us rolling!
 

/* Resize the big thumbnail from the Course Detail Page */

.course__detail__asset {

    width:30%;

}

@media screen and (max-width: 768px) {

    .course__detail__asset {

    width:100%;

    }

}

​@giovanna.orlando ​@Philcahill87 I didn’t see that Phil had replied at first but glad to see code share coming out of the coffin and into value added service.   Thanks team.

​@giovanna.orlando Thank you for sharing this!! It looks so much better smaller like this. 

Thanks ​@LisaRollins ! We are really happy how it turned out.