During sfira (and the 3 weeks), I find that my neck gets extremely uncomfortable and itchy from not shaving (and not very presentable). Is it permissible to "clean up" or even out my beard by shaving my neck? Is hair on the neck considered part of the beard? And is only the beard assur to shave during sfira, or is any hair?
See this article . My inference from this is that considering that there was a debate regarding shaving in general, plus even for those opinions that prohibit shaving, there's a debate if that means only the beard, there are leniencies to rely upon regarding shaving your neck.
As there is no consensus, from what I can tell, CYLOR.
If you DO shave your neck, don't stick it out for others too much ;-)