I presume that you mean there is a few inches of cord left attached to the kitten, rather than the whole cord still attached to the afterbirth? If so it will shrivel up and drop of within a day or two, although most cats/dogs chew them off much shorter or they break naturally. If they pull them or chew them too short it can cause an umbilical hernia, so don't interfere unless the cord is getting caught up and pulling.
I expect by now you will have found that out anyway!