All seems like "fix tests" is the better advice.
Flaky test? Fix it! Make it rock solid! Slow test? Fix it! Make it fast! That can be hard (if it was easy, people would have already done it), but it's vastly more useful than deleting.
Even the mentioned overtesting requires a fix by focusing the tests on separate things. You could call that "deleting" but that's oversimplifying what's going on. Same with changed requirements.