Hi.,

Do you want to hide a featured image under the blog template page http://prntscr.com/j223ly ? then get into Admin Panel > Appearance > Humanity Options > Integration > Custom CSS > Enable Custom CSS > Yes > Pasted the below css code inside the text area > Save All.

.entry-thumb {
    display: none;
}

If you want to hide the featured images in the post details page then you can disable the feature image under the post page ,

Refer : http://prntscr.com/j224f2

Else if you are referring to something else, please let us know a screenshot/video so that we can help you better.