This question has become important to me recently. As a psychic/witch/sorceress I frequently come in contact with many types of entities . Many of them seem confused when they realize that although they spend hours days years around people the people have no real idea who or what they want. Here are some things that sometimes rattle me and let me know someone dead is in proximity. They may seem simple but they do little harm and paint a clear picture.
Doors acting strange. Locks sticking. Wind blowing them open for no reason
Car engines not starting and then seeming to start by themselves.
Insects buzzing loudly for a few seconds or minutes
Food suddenly turning sour
If you want to be gracious to your family and friends please just send them one of these signs and pass by. They will remember you kindly.
They will pass on to the nether world in time, but that is a good question you ask.
They're already dead, so I can't see that being direct and truthful can hurt them any more.
I mean, it's kinda like dealing with kids. You've gotta be gentle but firm. "No, put the lamp down. Stop messing with my lunch. Don't mess with those bugs." Move on and you can have ice cream. Pretty much every other option is full on exorcism, to the best of my knowledge.
I don't think you really "hurt" them much either way.
In my way there is a passing ceremony. Usually at the burial, but really can be done any time.
Your not sending them away your pointing out the door.
My sisters mother was a dense women in life and didn't improve much in death. I just point blank told her she was dead and she need to go find her husband and the door is that way. Worked she quit waking me at 3 a.m complaining there was something wrong.
KINDNESS is the best answer. It's totally possible that the ghost doesn't realise it's dead. Sometimes all you need to do is smile and bow slightly to just acknowledge their existence. If they continue to hang around you pay more attention to what their are doing ...it's possible that they need something from you or may be trying to communicate. Always be kind to spirits and ghosts because they may have an evil side. May you have a peaceful Journey ... Mike