What's actually true?

Your word overrides mine. Nothing is overwritten — the old version stays on file with a closed validity interval, and the briefing starts using the new one.

Erase this for good?

What it said is destroyed, not hidden — the one thing on this page that cannot be undone. All that stays is a mark that something was erased, and when, so the erasure itself is provable. Briefings, nightly summaries and questions that repeated it go too. It leaves the record now; the backup copies that could bring it back are gone within seven days.

This forgets it; it does not forbid it. If you say the same thing again it will be recorded again, as a new fact with a new date — nothing of this one comes back with it. There is no way yet to tell Stillbay never to store something, so if you want it kept out, keep it out.

Unlink this sign-in?

Apps you connected through it lose the sessions they hold in your name, and will ask you to sign in again. Nothing on your record changes, and you can link the same account again whenever you like.