Anybody can, signed in or not. It goes straight to whoever looks after the record and nowhere else.
If you want something taken down, say so here and it comes down while it is looked at. You do not have to explain why.
The record holds people who have died and nothing about anybody living. If something has got in that should not have — about you or about anybody else — this is the quickest way to say so, and it is treated as the first thing of the day.
What you write is kept so that somebody can act on it and write back, and is read only by whoever looks after the record. It is not passed to anybody else and it does not go on the site. What can and cannot go into the record.