Unregister metabox on Custom Post Type

functions.php

<?php

//* Unregister metabox on Custom Post Type

function afn_remove_custom_taxonomy() {
	remove_meta_box('video-category'.'div', 'video', 'side' );
	remove_meta_box('video-tag'.'div', 'video', 'side' );
		
	// remove_meta_box($custom_taxonomy_slug.'div', $custom_post_type, 'side' );
       	// $custom_taxonomy_slug is the slug of your taxonomy, e.g. 'genre' )
       	// $custom_post_type is the "slug" of your post type, e.g. 'movies' )
}

add_action( 'admin_menu', 'afn_remove_custom_taxonomy' );