Why do I see a forum topic/post after deletion?

The chances are that you have some cache enabled for this module so even though the post/topic has been deleted there is still a chance the post is in the cache.

This cache setting can be changed along with other module cache settings in the main site preferences within the admin section.

This Q&A was found on XOOPS Web Application System : https://xoops.org/modules/smartfaq/faq.php?faqid=422