Green’s Dictionary of Slang

1. to knock unconscious.

1829

Pierce Egan’s Wkly Courier 22 Mar. 4/1: It was 7 to 4 against Reedy; who had, but an hour previous, quitted a cove in Leivester-fields.

2. (orig. US) to die.

1939		R. Chandler ‘Trouble Is My Business’ in Spanish Blood (1946) 198: Quit cold—with a slug in his head.
1962		B. Jackson Get Your Ass in the Water (1974) 114: You know I’m sick/ and ’fore I’d suck your pussy, bitch, I’d just downright quit.
1998		P. Cornwell Point of Origin (1999) 62: ‘Until that Coke machine out front quits,’ the woman said with a wink.