Hello Anu!

According to the guidelines of NTA, anything carried by the candidate, that can arouse suspicion of probable cheating in the examination, is prohibited in the exam hall. With the advancement of technology, recording and telephonic devices have kept decreasing in size, so small that they can be hidden even behind shirt buttons. While it is not in my knowledge if long and colored nails can be brought in use for carrying out such malpractices, it is better not to take any risks on the day of the examination. So it is better if you remove the nail polish and cut your nails short. There is enough time to do that since the exam is 2 days away.

All the best for your exams!