release to netherworld not working

One of my sims just died. I was given the option of making her a playable ghost or letting her go into the neighbourhood. I don't want ghosts in my game. With either option, when I clicked on her grave, there was no option of releasing her to the netherworld.

And then another ghost turned up at the house. I didn't want to actually delete it, in case it mucked up someone's family tree. But I don't want ghosts in my game.

How can I get rid of them?