I can only find one way, hide it using CSS. Go to wp-content/themes/<your-theme>/functions.php, add the following before the closing ?> :

 

Jetpack has an answer for this. This is for self hosted WordPress. First, open your functions.php inside wp-content/themes/your-theme/. Add the following line:

You are done! Every time you want to post a new post, you will see a checkbox. Tick, if you don’t want to email your subscribers of your new post.