Green’s Dictionary of Slang

1. (US) to get married.

1902		Ade Forty Modern Fables 212: It is now the Practice in our most polite Circles to get the Groom good and Ory-Eyed about twenty-four Hours before he Steps Off.
1926		Wood & Goddard Dict. Amer. Sl.

2. (US) to be executed.

1927		D. Hammett ‘$106,000 Blood Money’ Story Omnibus (1966) 346: The old man and I are both due to step off if we’re caught.
2000		(con. 1940s–60s) Décharné Straight from the Fridge Dad.

3. (US) to die.

1939		R. Chandler Big Sleep 83: You can step off for it just the same.
1989		J. Morton Lowspeak.

4. (US black) to leave.

1992		T. Williams Crackhouse 152: steppin’ off to leave.
2016		A. Wheatle Crongton Knights 9: Anger surged through me. I had to step off.

5. (US teen, also step off on) to leave alone, to stop interfering.

1990		N. George ‘Pop Life’ in Buppies, B-Boys, Baps and Bohos (1994) 98: Pops stepped off on Mom [...] fractured black families were hardly an unusual event.
2002		Teen Lingo: The Source for Youth Ministry 🌐 step off 1. a retort used to warn someone to back away. ‘You betta step-off!’ 2. To threaten someone to leave one’s belongings alone. ‘Step off my back pack!’.