to tear off; to pluck; to scratch off
痒くて肌を掻き毟った。
My skin was so itchy that I scratched it raw.
苛立ちで髪の毛を掻き毟っていた。
He was tearing at his hair in frustration.
子供が痒い湿疹を掻き毟らないように注意した。
I warned the child not to scratch the itchy rash.