I don't delete unfinished saves that haven't reached a natural end, as in the sims dying of old age, since I don't keep succeeding generations in the same household as their parents. I move them to a folder I made for saves I'm not currently playing. I did have one save where my original sim's husband died of old age, and she lived on and on after her life expectancy had passed. I finally couldn't play her anymore, because her life seemed too lonely, after being with her husband for so long. But I didn't delete her save either. She's still in my saves on hold folder, where I could return to her again, if I ever decide to. Not all of my saves on hold are on my computer. I have a removable hard drive for storage, and all of the older saves are on it.