Leaders and Co-Leaders changing Green to Red is a basic want in post-war management. It beats the "Kicked because you didn't do your attacks". It's also good when someone is informed out of game that someone is away for a little while.

Changing Green to Red, not wanted, don't do this. If done by accident it could be really confusing or even distressing.

I suggest that when someone changes someone else's Opt In status to Out, it is auto-reported to chat. It will save having to announce manually that it was just done. When managing the clan like this, transparency and timely communication is important.