Iām not sure there s a real border. maybe you only see a placeholder border which only shows a picture placementā¦ but nevertheless you can adjust border styles following this procedure:
Are you sure the border isnāt actually in the image itself, or even part of the logo? Because the line of the border looks exactly like the line at the bottom of the logo.
What I have noticed though, is that when images have a transparent background, LibreOffice on the desktop shows exactly these borders, which I think are there to indicate where the actual image borders are. These borders donāt show up on prints or PDFs you generate from the document.
The strange thing is that the borders donāt show up for me in Collabora, and I havenāt found a way to turn them on, nor have I found a way to turn them off in Desktop LibereOffice. But that could just be me not finding the right setting