If you are in the EU and press delete and the database owner (data controller) does not delete the post then the database owner is now breaking the law. As of ?may? this will carry significant fines.
There are plenty of cases where a system would not function correctly if you are actually erasing DB entries when a user clicks the delete button. In many cases, even the users themselves might expect to be able to undo or go to a delete list and see entries that were deleted.
EDIT: In my layman's opinion pressing that button is an explicit request to delete the data. Also the kind of behavior you are suggesting is not private-by-default and goes against the spirit of the law. I don't think that a judge will look kindly on it.
I am not a lawyer. I am not your lawyer. I suggest that you consult a lawyer.
That being said, the jury is still out on whether the EU can successfully collect fines from exclusively US based companies.
Large corporations like Google or Facebook have a presence in the EU and can be fined directly. Good luck in the courts enforcing gdpr to US only companies who have no servers or physical presence there. I imagine it will be a difficult process and not worth the effort in most cases.