Hi tmrmarketing,
thanks for using MH Magazine lite.
You could create a child theme and then copy the file content-single.php to your child theme and delete this line of code in that file:
mh_magazine_lite_featured_image();
That will remove the featured image on posts, while still using the featured image for the thumbnails on archives and widgets.
As an alternative (in case you don’t want to touch code), the premium version of MH Magazine includes an option to disable the featured image on posts, as well as several other additional features, options and custom widgets to customize your website.