Hey there,
I am really sorry for the delay of this reply as it is a weekend for us here.
You can't just renamed this placeholder image file from JoomlaFolder/components/com_easyblog/themes/wireframe/images/... , it will show broken image on your entry page, can you rename it back? because I was unable to connect with your FTP server, you provided that password is incorrect.
The reason why it populate that image placeholder on the blog entry page is because by default the system will check if your blog post whether got post cover or not, if don't have, it will display placeholder image on the page.
If you would like disabled that placeholder image, you have to disable it from backend > Easyblog > setting > views > entry layout > placeholder image - NO, but based on what i checked on your site, it seems like you do not want to inherit the setting from the view, so it will refer back what you configure the setting from your category which is "Blog" category setting page.
I already disabled this for you, can you check your blog entry page, do not show the placeholder image now.
Regarding with your frontend listing page do not show the image is because that blog post do not have any post cover, so it will not show the image on your listing page.
Hope this explanation will help.