If they saw the note on Damus, it will also be in their local cache. I think you have to delete the app and a reinstall it to clear the local note cache. It’s also possible it’s on other relays out there. The delete tool doesn’t send a delete request to all relays. Also, some relays ignore delete requests. 

 Gotcha. I was able to verify that it was removed from a couple of them using https://nostr-delete.vercel.app/