It is Haram (prohibited) to shave one's beard, because the Messenger (peace be upon him) ordered Muslims to let their beards grow. Thus, if he shaves it, he will be disobeying the Messenger (peace be upon him). Also, shaving one's beard involves imitation of disbelievers and Muslims have been prohibited from imitating them in addition to other prohibitions. Moreover, it is Haram to befriend disobedient people and not reject their deeds. However, if someone shaves his beard, it will not be Haram to eat from his sacrificial animal, because this does not take him out of Islam, and the same goes for befriending disobedient people.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.