Green’s Dictionary of Slang

dakma v.

[ety. unknown]

(US Und.) to silence.

[US]Matsell Vocabulum 24: ‘Dakma the bloke, and cloy his cole,’ silence the man, and steal his money.
[US]Trumble Sl. Dict. (1890).
[Aus]Crowe Aus. Sl. Dict. 22: Dakma, silence.