During Jesus' time on earth it was customary to wear beards. Christians came first from a Jewish background, and Jewish men wore beards. Beards were a sign of maturity, wisdom, and piety.
Today Christian ministers, like the early Christians, are concerned with neatness and cleanness, but they strive to dress inconspicuously, so that their appearance does not in any way detract from the dignity or the effectiveness of the message they bear. (2 Cor. 6:3, 4) In recent years in many lands a beard or long hair on a man attracts immediate notice and may, in the minds of the majority, classify such a person undesirably with extremists or as rebels against society. God’s ministers want to avoid making any impression that would take attention away from their ministry or hinder anyone from listening to the truth. They know that people are watching true Christians very critically and that to a great extent they judge the entire congregation and the good news by the minister’s appearance as a representative of the congregation.
Jehovah's Witnesses - Are Wearing Beards Discouraged? (Defending Jehovah's Witnesses)
"Would it be proper for Christian men to wear a neatly trimed beard? We all know in biblical times Christian men had them including Jesus." (JWQ&A)
Appearance (Physical) (SFBT)