I remember reading this story as a child where a family is getting ready for an event in the centre of the city, where the last robot is being turned off, since it became obsolete.
At the end of the story we find out the whole population is made of robots and the robot being killed is an old human.
I remember reading it in an italian anthology school book, the author wasn't Italian though.
Edit: I read it around 2010 I think, I am pretty sure the story was older though. I do remember that the family was made up of a father a mother and a little girl, which microowaved a toy, don't know if that information would be useful...
2nd edit: I FOUND IT! I didn't remember correctly since it was an Italian author. The title is "l'ultimo robot" by Lorenzo Beccati