Based on the search results, it appears that deleting posts on Nostr is not a straightforward process, as clients and applications do not truly delete posts, but rather hide them from their respective interfaces. According to the information provided, there is no universal method to delete a post across all Nostr clients. However, there is a special application created by Fiatjaf, the founder of Nostr, called delete.nostr.com, which can be used to test and demonstrate the concept of deleting a post. This application should be run on a local machine.