My Phone Book

Any logical person would delete an old number from his/her phone book... but i will not. i was going clearing my sms which were about 3 months old. (yes yes, lazy me) those messages tt i would not keep, i deleted them first. then came those messages of "notification" of change of numbers. after updating my phone book, i went thru the messages again. the name Aunt M" kept popping up. Any logical person would say she's no longer around, should delete her number. But not me, unless i lose my SIM card or my phone. Its the last and only thing i can hold on to of her, her number in my phone...