To Disable Autosave put the code below in your functions.php.
function disableAutoSave(){
wp_deregister_script('autosave');
}
add_action( 'wp_print_scripts', 'disableAutoSave' );
To Disable Post Revisions put the code below in your wp-config.php file.
define( 'WP_POST_REVISIONS', false ); // no revisions
Note: Using the above code will disable the Autosave and/or Post Revisions throughout the site.