Don't show ADMIN NAME below every post

I would like to get rid of the admin name that shows below every post. So I added this code:
.page-id-4642 .blog-author {
display:none;
}
But then it only gets rid of the admin name on my blog page. When I click on a post, the admin name still shows below every single post I’m creating. So I have to add
.postid-WHATEVER .blog-author {
display:none;
}
for every post I’m creating? That cannot be the solution.
Is there a way to get rid of the admin name on the entire page, so I don’t have to add this code everytime I create a new post?