Dew claws serve basically no purpose in domesticated animals.
Taggart has all four dew claws and usually they would remove them while he is under getting neutered. But ARF did not do that. My vet said not to remove them unless something happens to them (like ripping them off or something). She said it is horribly painful and not necessary to remove them.

I would think the same would be true for cats. If you can't get the nails clipped the vet can do it for you. I had to take my friends cat to the vet because I didn't feel comfortable doing his myself. My cats I can do with Bruce's help. Taz I was able to do by myself.