No. And simply put, this is because of the nature of the fediverse. You post something then it's on anyone listening's server. Lemmy or otherwise. Now, when you delete you send a delete request to all of those servers too.
Here's the thing. What if someone forks Lemmy or just has their own server type. They don't HAVE to implement delete. It could still be there. Maybe it's hidden, but it's there.
Now assume any government or corp is listening to the fediverse.
So no. We're open, no one can take us down, but, know that anyone can listen, and they can do whatever they want