Hello,
These links could be in the main menu. Don’t know another place. But I see that you already replaced the menu links. So, try to finish your site and replace all the demo content, and scan after that if you still have them.
Unfortunately, we don’t have the option to add the link for the size guide instead of the image. You can either use lightbox to show the image or the Download button. There is no option for a simple link.
Regards