And the Nazarite shall shave the head of his separation at the door of the tabernacle of the congregation, and shall take the hair of the head of his separation, and put it in the fire which is under the sacrifice of the peace offerings. (Numbers 6:18)
The shaving was done beside the slain peace offering (cf. Lev. 3:2), and the hair cast into the fire of the sacrifice on the altar that stood before the door of the tabernacle (Ex. 40:6). The hair had been dedicated to Jehovah; therefore it was destroyed, to eliminate any danger of defilement.