Deleting Featured Images in Posts

I’m installing a new theme and one features is having featured images on the front page. I’m connecting to my blog page which is having post images overwrite the featured image in the main page. I’ve gone into the posts to remove “featured image” to find there was not a featured image to begin with. I’ve looked into the image itself on the post, but there is no option to make it a featured image.

I’m not sure how to proceed except removing featured images from posts with code.

Does anyone have any suggestions?