An even better solution is to use WordPress built-in return false shortcut, this way you don’t have to create a empty function each time.
add_filter( 'bbp_get_single_forum_description', '__return_false' );
add_filter( 'bbp_get_single_topic_description', '__return_false' );
Thank you! I did the same…copy pasted the shortcode from this page! And was desperatly trying to find how to remove this non-html5 tag from bb-press!
You saved my day!