Green’s Dictionary of Slang

(orig. US) let go!; occas. as v.

1889		J.K. Jerome Three Men in a Boat 24: ‘What are you up to,’ he retorts; ‘leggo, can’t you?’.
1901		Bulletin (Sydney) 21 Sept. 11/2: Annie, of whom he has leggo, now wants maintenance as a deserted wife.
1931		N. Van Patten ‘Vocab. of the Amer. Negro’ in AS VII:1 29: leggo. W. v. Let go.
1957		Galton & Simpson ‘The Old School Reunion’ Hancock’s Half-Hour [Radio script] Ow my ear, leggo you beastly rotter.
1977		G.F. Newman Villain’s Tale 94: ‘Leggo, you stupid cunt!’ Hayes screamed [...] Eventually he did.