That mix looks very wet. I don't water until my mix feels crunchy. I use clay pots and I can see how plastic would keep yours wetter (slits or not). I would cut them off but someone more experienced will be along if you can be patient...
I agree with what everyone said. I thought at first that the last leaf had fallen. My little lady orchid (kylo) does well in the cooler conditions/Sphagnum moss but I water it about once every two or three weeks. It doesn't hurt these to be a little on the dry side with the cooler temperatures and the sphagnum moss.
As Carol said, Phals in moist medium tolerate cold temperatures even less well. Phals in mixes with a lot of sphagnum are best watered by just moistening the top of the sphagnum, not soaking all the medium. The water will distribute through the pot. In this way the sphag stays barely damp and there are plenty of air spaces remaining. Let it get quite dry before moistening again.
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Thank you everyone for your advice. I will try not watering it for the next 2 weeks or so and see how it fares. Should I try to cut off the black roots?