wp_ajax_delete_tag
if ( $tag_id == 21 ){
wp_die( -1 );
}
add_action( 'pre_delete_term', 'wp_pre_delete_term', 10, 2 );
unction wp_pre_delete_term( $term_ID, $taxonomy_name ) {
$slug = 'pro-plus';
$category = get_category( $term_ID );
if( $category && $category->slug == $slug ) {
wp_die( -1 );
}
}