roach, v. — Green’s Dictionary of Slang

roach v.

[SAmE roach, to cut (a horse’s mane) short, so that it stands up like the bristles of a hog]

(US) to cut one’s hair very short.

1900		Ade More Fables in Sl. (1960) 130: He stopped roaching his hair.
1909		L.W. Payne Jr ‘Word-List From East Alabama’ in DN III:v 364: roach, v. To comb or brush (hair) straight back from the forehead; also to come up out of water so as to sweep the hair back thus.