The Attachment Image is added from your end so it can only be deleted from your end under the Topic and don’t worry the Attachments and the info shared in the Private Content field is only visible to Logged In users of the Forum i.e. You and the Support Agent.
Regarding your mentioned concern, we have checked your Site without Login too. The Logo and Search is appearing fine there too: https://snipboard.io/m3t4NQ.jpg
So, it might be a Cache issue at your end in this regard because as we are seeing, things are appearing fine on your Site with and without Login.
Please check back your Site after completely clearing browser and server cache.