How to remove Featured image from Blog posts page

I hope I explain this correctly. When I post to our blog page and do not add a featured image, the thumbnail is blank. I am forced to display the featured image. How do I display the featured image in the thumbnail but not display it on the page?
https://weclean.co.za/blog/ – this is the blog page feed where the thumbnail must be displayed but I want to remove the featured image from all of the posts.
Is there some css I can use to do this? I have searched other threads but those options do not work such as this:
.blog .entry-thumbnail { display: none; }