I suspect that those three have a root system that was not large enough to support the entire plant and a balance must be kept, so a portion of the evergreen has failed. If the wood is completely dry and no sign of life is there, go ahead and remove the branch. Surrounding good wood now exposed to the light will create new buds and begin to fill in. Depending on your weather, be sure to water them late into the season to ensure adequate soil moisture for the winiter.