Do you want to disable all emails (with no exceptions) sent from your WordPress site? Do you absolutely not want your site to send any emails?
Here’s the code snippet:
add_filter( 'pre_wp_mail', '__return_false' );
Add this snippet to your functions.php and your site will stop sending emails.
Do you want to NOT send emails but conditionally? Here’s how to disable emails you don’t want to be sent from your site.
I hope this helps!