Wait and see what happens. You don't need to cut it off right now. Even if that whole leaf dies, losing one leaf usually won't kill a phalaeonpsis. Good luck.
You will have to cut the leaf 1/4 below the brown. To be on the safe side, treat the cut with isopropyl alcohol.
You won't kill your orchid this way. It is like pruning a fruit tree or havesting herbs. The phal will grow a new leaf soon, then another, and in a few years, you won't even notice. They do grow slowly so you will need to be patient. Good luck!
Leave it for now, there is plenty of green left to help support the plant. Eventually it will fall off naturally. It only looks bad, most is still green. I'd leave it alone. For what its worth.