Simple Share Buttons Add Plugin and Custom Post Type

Here is the solution :

You need to hook an action to remove ssba button. Wp action runs pretty early and allow you to remove the ssba filter on the content which add the buttons list.

function remove_share_buttons_custom_post() {
  if (in_array(get_post_type(),array('sar'))) {
    remove_filter( 'the_content', 'show_share_buttons');
  }
}
add_action('wp', 'remove_share_buttons_custom_post');