AC delete works on 4 bangers, but that's about it. And when I say works, I mean it's a noticeable change. My DD is a 4 banger and I'll turn off the AC before the light turns green haha. Not that I'm racing, but you can feel the difference.
As far as deleting, if it's dead, I'd delete it. The little defroster setting tries to use the AC a little. I had an old car that AC was going out on. It would clickity click like crazy. So I just didn't use it. But then when winter came, I'd turn on defroster, and clickity clack came back. That's when I learned defroster uses AC even if it's set to hot or warm.