IIUC you only need to semantically "delete" it, ie. record the fact that it is deleted, and then not use it. Consider an analogy to a filesystem. If I delete a

IIUC you only need to semantically "delete" it, ie. record the fact that it is deleted, and then not use it. Consider an analogy to a filesystem. If I delete a file, the bits aren't actually gone and are recoverable (at least for a while). But no-one (as far as I know) is saying we need to scrub or smash hard drives to pieces on customer request. We simply tell our storage system not to present this information to us anymore. Similarly, in any immutable log based system (like many databases), you wouldn't delete a record by actually removing the information - instead you write a tombstone that says "this information was deleted", and then queries will not return it. If you're using the blockchain to store information, then you simply need to teach your system that retrieves that information to recognise some kind of tombstone, and you need to honor that tombstone. It's besides the point whether anyone else continues to use the information, similarly to if you'd published it on your website then someone had copied it - even if you delete it, other people are under no obligation to also delete it.