Add the following lines to your WordPress Theme’s template functions.php file (For example, functions.php file for a Theme named “default” would probably reside in the directory wp-content/themes/default/functions.php) or create it as a Plugin by filling the additional Standard Plugin Information:
<?php
global $pagenow;
if (in_array($pagenow,
array(
'post.php', // Edit Post
'post-new.php', // Add New Post
'page.php', // Edit Page
'page-new.php' // Add New Page
))) {
wp_deregister_script('autosave');
}
?>