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.