Just a random thought on how Buddhism would view the custom/practice of “hair removal.” (a) Of course, we know that according to the Vinaya, monks and nuns must shave their heads and beards/moustaches. It is said to be a sign of “renunciation” (or Vinayic asceticism). Lay Indians usually must have kept long hair and moustaches. But monks and nuns are not supposed to shave their other body hair, mainly, pubic hair. Perhaps shaving pubic hair was rather seen as related to sexuality and sensuality. Lay people in ancient India seem to have shaved even pubic hair. Thus the rule in this case seems to have been the reverse of the custom of the laity. (b) If I remember correctly, Sa-paṇ discusses the issue of shaving “eye-brows.” According to some Vinayic traditions, it is a transgression to shave eye-brows, according to others, it is a transgression not to shave eyebrows. (c) Now what about the case in Mantric forms of Buddhism? According to the Subāhuparipṛcchātantra (cited by Rong-zom-pa) and which is said to be a Mantric Vinaya, prohibits shaving of any body-hair (p. 297): byin pa dag dang mchan khung spu rnams ni || lag pas kyang ni btog par mi bya zhing || me yis mi bsreg spu gris breg mi bya || spu med bya phyir sman gyis mi byug go ||. Interestingly, this text reveals several ways of hair-removal and various kind of hair that people must have removed. Removing hair with fire (for example facial hair or hair in and around nose and ears) is perhaps not uncommon amongst some Middle-Eastern or Kurdish/Persian barbers. The text also suggests that people even used hair-removing ointments or creams!
For Mantric practitioners (particularly when they are in strict retreat), shaving hair would be an act of artificiality and vanity, or at least a waste of time. What happens if such a Mantric practitioner happens to be someone ordained? In Tibetan traditions, there seems to be at least two positions or rather practices. Most monks and nuns would at least shave their heads even when staying in strict retreat but by all means once the retreat is over. But some bKa’-brgyud monks seem to keep their long hair even after the Mantric retreat is over. During my stay in Dharamsala, I often met a bKa’-brgyud yogin, a dge tshul who wore normal monk’s robes but kept long matted hair. Once while attending the fourth-nightly confession ceremony (gso sbyong) in the mTshan-nyid-grwa-tshang, I happened to see that yogin. He, too, was attending the gso sbyong, wearing chos gos, like everyone else in the gathering but with his usual long matted yogic hair. With such abhor, one dGe-lugs monk tugged at his chos gos, and whispered contemptuously: “What are you doing here, you disgrace to the Buddha’s doctrine?” (’dir ga re byed kyi yod, bstan pa’i zhabs ’dren khyod). While my heart ached for the yogin, I could also understand the monk's horror (though not his contempt) at seeing a yogin (clad as a monk) with long matted hair attending the gso sbyong!