Could you give us a specific page link or a screenshot of which part you are talking about that has this issue please to help it out?

Best regards,
Konstantinos

Let’s do some overrides to your CSS shall we?

.post-standard .post-header {
margin-top: 0px !important;
}

.post-standard .post-img {
display:none !important;
}

Those will take care of the gap but still you’ll see you are like 2-3 pixels away cause your sidebar uses a border that sits on the ‘outside’ of the box. If you want that too do

.post-standard {
  margin-top:-3px !important;
}

This selects all ‘post-images’ under any page that is a standard post, so be aware as I don’t know your theme you might want to add extra classes for better targeting in case it removes any other photo somewhere :).

That should do the trick.

Best regards,
Konstantinos