How do i deactivate "Your comment has been posted." after user posted a comment
you can add a custom submit handler to the comment form using hook_form_alter():

function yourmodule_form_alter(&amp;$form, &amp;$form_state, $form_id){
  if( $form_id == 'comment_form' ) { // find and use the actual form ID
    $form['#submit'][] = 'yourmodule_your_custom_comment_submit_function';
  }
}


Then in that submit function check to see if the message exists using drupal_get_messages():

function yourmodule_your_custom_comment_submit_function(){
  $message = drupal_get_messages('status', false);
  if( $message['status'] == 'Your comment has been posted' ) { // Or what is the actual message
    drupal_get_messages('status');
  }
}


This is for Drupal 7 but these functions exists in older drupal versions. Check api.drupal.org for details.