@Saadi Muslu I wish that I could help but I tried experimenting and didn’t see a way to clear a previously used image in an email so that it won’t load for others -- hoping this issue doesn’t cause too much of a problem for you!

I’d recommend reaching out to support if you haven’t already, maybe they can help escalate something like this -- surprised there’s not a media library where the file could be edited or updated but I couldn’t find anything quickly. 

If you delete it from the current version, it seems the image is still retained in the history but I hope you get the help you need.