Old sim won't die.

ive had elders die of woohoo before. at least they go in a good mood. lol

I had one live nearly double the normal life span for a sim. On normal I think they get between 125-150 for some of mine and have had them live to nearly 300 days if they are physically fit and did the bodybuilder aspiration. I had one of my sims marry Dina Caliente and she lived to 437 days but I think she glitched or something because I don't think that's normal even for the bodybuilder trait from the aspiration.

Is it not possible to cheat away that trait?

I use the UI Cheat mod, which is perfect for killing off sims. All you need to do is pulling their hunger bar all into the red, and they will collapse immediately. I try to be a bit more human though (no mod needed), by rather dressing them in winter outfit and sending them outdoor during a heatwave, or summer outfit sending them on a walk during a freezing snow storm. Takes only a couple simhours and it might look better in the family tree to die from a heat stroke than from hunger. ;)

A couple of people have suggested death by woohoo... but this is not possible with the Long Lived trait. They are immune from exhaustion.

The ones that I don't have an answer for are the bugged townies from City Living. I have had several of them join my game but they do not age naturally so I just try to keep track and age them up manually. I haven't gotten to the stage during which they die. That will be awkward because I don't "cause" any of my sims to die. If the grim reaper comes then that's nature taking its course.

For a few of them, I tried removing the "IsWeirdo" trait but that didn't work.

I had two elderly Sims sharing a household. The younger one has died already and has turned up as a ghost. The older one is expecting the Grim Reaper to appear any minute now, but I guess her Fitness is holding him off.

How high is his fitness skill? I think the higher the skill the longer they live.

If you have mccc comander you can use it to see how much longer they have to live. I was trying to do mermaid legacy challenge and I had a whole house full of elders. finally checked it out and it turned out that the mermaids had like 30-40 "bonus days" they got to live beyond the regular elder lifespan.