Remove 'Add Media' button from above WP editor, per post-type

wordpress-remove-media_buttons.php

function check_post_type_and_remove_media_buttons() {
	global $current_screen;
        // use 'post', 'page' or 'custom-post-type-name'
	if( 'post' == $current_screen->post_type ) add_action( 'media_buttons_context' , create_function('', 'return;') );
}
add_action('admin_head','check_post_type_and_remove_media_buttons');

Here is another way
$settings = array('textarea_name'=>'Overview[Notes]') ;
$settings['media_buttons'] = false;
wp_editor( htmlspecialchars_decode($text), 'mettaabox_ID2', $settings );