I have same problem and want to remove that advertising panel ie. BWS panel.So as you said it cannot be removed i taken it as a challenge i found two solutions to remove it.
1) Using CSS : You can hide this panel’s menu from you admin menus using this function in your plug-in(I have hidden it for users rather than super admin.
add_action( 'admin_init', 'remove_aws_menu');
function remove_aws_menu(){
if(is_super_admin())
return ;
?>
<style type="text/css">
#toplevel_page_bws_panel{display:none;}
</style>
<?php
}
2) Custom Plugin : BWS plugin have an function named as 'bws_general_menu' in deprecated.php file which adds this menus and remove_menu_page() function cannot remove it.So in your custom plugin create a same function so bws menu function will not execute and menus will not be added,instead you function will be executed where you can return anything you want.
Here is a function with same name as BWS.
function bws_general_menu(){
return;
}
