Visibility of thumbnail picture in post

Hello!
I’ve just downloaded Nisarg motive and I’m already happier than with the previous one ?? But i have one problem: is it necessary for the picture i’m using in thumbnail to apper at the top of post it refers to? I would like to remove it, sice the same picture is used somewhere else in the post. I’ll be grateful for response!
Have a great day and take care of yourselves!

The page I need help with: [log in to see the link]