Remove capability doesn't remove media button in edit.php

I removed Author capability to slideshows plugin, but when i log in as author inside edit.php (articles editor), i still see the media button to insert slideshow shortcodes.

<div id="wp-content-media-buttons" class="wp-media-buttons">
<a href="#" class="button insert-media add_media" data-editor="content" title="Aggiungi media"><span class="wp-media-buttons-icon"></span> Aggiungi media</a>
<!-- need to remove those 2 elements <a> and <div> -->
<a href="#TB_inline?width=450&inlineId=insertSlideshowShortcode&width=640&height=354" class="button thickbox" title="Insert a Slideshow" style="padding-left: .4em;">
	<img src="http://www.mysite.it/wp-content/plugins/slideshow-jquery-image-gallery/images/SlideshowPluginPostType/adminIcon.png" alt="Insert a Slideshow" style="vertical-align: text-top;">
	Insert Slideshow
</a>
<div id="insertSlideshowShortcode" style="display: none;">...</div>
</div></div>

is this a bug?
is there a way to remove this button with a script in functions.php?

thanks a lot! bye

http://ww.wp.xz.cn/extend/plugins/slideshow-jquery-image-gallery/