Getting rid of "Welcome to Heavenly" featured image on home page

My home page (which is the page that has my latests posts) has the default image showing a picture of an iPad and the words “Welcome to Heavenly”.

I cannot find anywhere to get rid of this image entirely (or even to replace it with a slider or a photo of my own).

I don’t want a big image or a slider or anything on my home page; I want just the text of my posts.