So, theres no way to permanently delete a post from the Steem blockchain but you can delete a post from being viewable to others on the site. Simply edit your post and the post title and delete all the content within the post. The final step is to use "spam" as the tag(topic) and you should be good to go!
Let me know if you have any questions and make sure to upvote if you found this post useful!!
Have a good weekend!
Derek Cahill