There are a bunch of ways to get rid of ghosts, but you have to get rid of ghosts before they scare you to death!!
1. Take their gravestone and drop it off at the cemetery.
If they don't have a gravestone. Then take the ghost to the cemetery by clicking of your car and clicking go to community lot with.. then click the ghost's name. Then jog to your house with your car in your inventory. You now are ghost free:)
Chat with our AI personalities
Previous message here was: You delete the ghost's tombstone.
However, I've tried deleting and even selling it (by placing in family inventory & clicking sell all) but nothing worked. My guess is this may work if the Ghost returns to their tombstone, but if wandering your house-deleting the tombstone doesn't get rid of them.
The only thing I found to work is... using this cheat..
hold down control+shift+C, a bar comes up at top of screen,
type "cheatsenabled true" (exactly as is)
then type: resetSim and name of Ghost, ex: resetSim John Smith
This cheat seems to be case sensitive-so be sure type as above using spaces, etc.
You will need to download the Sims 3 Nude Patch to remove the blur.
You can't
go to the graveyard after dark, you have to catch the actual ghosts(the ones that are like transparent sims, not the spirits that look like halloween ghosts)
Put them in your yard and every now and then they will come out.
To get rid of a robot on Sims 3, you must first go up to the robot and argue with it a lot. Then once you've fought with it enough, it eventually flat out hates yu and leaves.