The whitish things with green tips are healthy roots. Don't cut those. The shriveled brown roots can be removed, Those look like typical victims of over-watering. Any brown or yellow leaves can also be removed. Anything that is healthy and green just leave alone.

The yellow mark sounds like typical sunburn. If the rest of the leaf is green and the spot is not soft and spreading, just leave it.

The plant looks basically healthy otherwise, though a little dehydrated from not having healthy roots IN the pot where they can do some good. It definitely needs repotting, and some fertilizer on a regular basis. Do you have some fresh potting mix for orchids and a somewhat larger pot with drainage?