In this short and simple post, i’ll give you the code which you can add to a new file named single.php and upload to the root directory of your child themes folder.
Best to use a code editor like Notepad++ when creating new files as it will enable you to save the file as a php file.
Other Options
You could also use a custom function and conditionally remove the footer widgets from all single posts using:
if ( is_singular('post') )