I agree and I will vote for it wherever I could so for the developer to understand that this is a necessary feature: ability to delete your own report (no matter what is it) and for the 'Not Here' button to stay longer on the screen so I can hit it after I pass the police or whatever.

This is a necessary feature. Having it go away in time is not acceptable. I don't want a single person put out by my mistake.

Sure would make waze more accurate if users could delete accidental reports!

when a hazard or police are no longer at that location, allow users to say that item is expired.

Ditto, very frustrating to not be able to delete a report I submitted that is on the wrong location (newbie mistake)

Sometimes the map issue I just reported was incorrect or I hit the wrong button. It would be nice if I could go back and edit or delete it.

Not necessary. If it is a map problem report, you just need to log into the editor, find the report and mark it solved and close it.
If it is a traffic hazard report, it will go away after a while because no one will confirm it.