+ // Remove book template usages
+ $this->queries->books->start()
+ ->where('default_template_id', '=', $page->id)
+ ->update(['default_template_id' => null]);
+
+ // Remove chapter template usages
+ $this->queries->chapters->start()
+ ->where('default_template_id', '=', $page->id)
+ ->update(['default_template_id' => null]);
+