Can't get rid of a hidden picture & Website availability error

Hey guys, I’ve got two issues I’ve been trying to resolve but couldn’t find out how to do it.

The first issue is in “Angebot” at the sections Executive Coaching & Business Schlüsselfähigkeiten. At each section there is a picture that I’ve inserted. But when changing screen sizes, a picture from the original template appears below and I can’t get rid of it for some reason. In the navigator there isn’t even a proper image file to delete that “old” picture that I don’t want anymore. How can I delete it?

The second issue is that fairly often, I can’t connect to the webpage even though on the editor it says that the site should be up and running. (Error message: safari couldn’t establish a secure connection)

Any help is much appreciated!

Here is my site Read-Only: