Remove featured image from category view and single post view

hi, i’ve tried editing template files such as single.php but i’m not able to locate the pieces of code which are responsible for showing the featured image of my posts in category view and single post view (before the post content). i need to remove the featured image from such instances as:

https://nextescape.co.uk/category/monthly-specials/

and the single post view:

https://nextescape.co.uk/2014/11/monthly-specials-dec-2014-christmas-cracker-2014/

i would appreciate the help, thanks.