I would list it in terminally critical condition (if there is such) meaning I think I see some flesh that could regenerate a new colony, but this unlikely as the recession of tissue is almost 100%. What caused this, are any other stony corals showing signs of distress?
It looks like there is still some living tissue at the bottom containing zooxanthellae. I would leave it be and see what happens. If the remaining tissue starts to appear healthier, then I would cut away the dead parts and let the coral recover.