For some reason my mermaid sims wont die, my second sim in my legacy challenger's wife has already died and she aged up after him so how shall I kill him?

seen from France

seen from France

seen from France
seen from Russia
seen from United States

seen from United States

seen from Germany

seen from Russia

seen from Germany
seen from Saudi Arabia
seen from Germany
seen from Türkiye
seen from United States
seen from United States
seen from Syria
seen from China
seen from Saudi Arabia

seen from United States
seen from United States
seen from Germany
For some reason my mermaid sims wont die, my second sim in my legacy challenger's wife has already died and she aged up after him so how shall I kill him?
Binx’s Legacy Challenge!
Strict Patriarchy: The Founder must be male. Only boys are eligible to be named heir. Female children cannot, under any circumstance, ever be the heir to the next generation.
Strict Traditional : To be eligible to be named heir, a child must be naturally born from their previous-generation parents and be able to trace an unbroken bloodline back to the founder. Adopted children may never be named heir.
Heir Law not sure if I should do random or democracy
Xenophobic – Heirs cannot be a different species from the founder or possibly tolerant occult so it can be any occult but not human