The effect of Nightwalker's Finger of Doom skill is:
The nightwalker points at one creature it can see within 300 feet of it. The target must succeed on a DC 21 Wisdom saving throw or take 6d12 necrotic damage and become frightened until the end of the nightwalker's next turn. While frightened in this way, the creature is also paralyzed. If a target's saving throw is successful, the target is immune to the nightwalker's Finger of Doom for the next 24 hours.
And Stillness of Mind:
Starting at 7th level, you can use your action to end one effect on yourself that is causing you to be charmed or frightened.
So, here's the scenario: My monk fails the saving throw for Finger of Doom and becomes Frightened, thus becoming paralyzed. Can he use Stillness of Mind to get rid of Frightened status and therefore freeing himself from paralyze, or he can't use this feat because of paralyzed status?