IDK why, but people in my circles don't ask that. But if they did, I'd probably say "I used to be a CPA and I worked in corporate accounting, but now I just stay at home."
But I have little kids. Even when they are older I'll still use the SAHP/homemaker line. I am female, but I'd do the same if I were male. (DH is a SAHP, actually)
I wouldn't be opposed to saying "I used to abc, but I saved enough and don't need to work anymore. I like to spend my time doing xyz these days..."
I probably will not use the word retired. I don't like it that much. IDK, it just sounds like old people stuff. I would say FI, though.