A Codicil to be effective in VA, it must met the same requirements of your will. However, Virginia does recognize holographic (i.e. handwritten) wills and courts generally will construe the language liberally.
The real question is why the need to remove one of your children as personal representative. (Though the better question would be why you wanted both listed as PR when the original will was drafted). While it might be burdensome to your out of state child they can certainly disavow the being executor if they feel that way and let your in-state child be the executor.