This is attachment, you can find it in the Dashboard > Media menu.
which id is: 497, you can find it and delete it. As I can see in Inspect element this is image: http://capptan.com.br/blog/wp-content/uploads/2018/07/engajar-e-reter-usu%C3%A1rios-de-aplicativos.jpg
But in your template, I can see you have hidden these things via CSS.
Hope you know how to delete it from Media.