Is it obligatory to obey one's parents and shave the beard, especially if they fear for their son in a country that is hostile to Islam?

Shaving the beard completely is forbidden, but it is excused in cases of necessity, as stated in the Almighty's saying: "And He has enumerated for you what He has forbidden to you, except for that which you are compelled to," and the Prophet’s (peace be upon him) saying: "Indeed, Allah has overlooked for my Ummah mistakes, forgetfulness, and what they are compelled to do."

So, if growing the beard causes certain or highly probable harm that cannot be averted except by shaving, such as killing or displacement, then it is an excuse. However, if the harm is minor or imagined, it is not considered an excuse.