iOS dictation is a great feature, which mostly works both for Siri and for apps supporting an onscreen keyboard.
However: is there a voice command I can use to backspace or delete the last word? I found a good guide here, but there is no delete command: http://www.siriuserguide.com/siri-dictation-guide/
Best Answer
It doesn't seem like it is possible.
The closest I have seen is to use 'shake to undo' which will then select your entire last phrase/sentence. It's then possible to adjust that selection & delete as required.
Not what you wanted, I'm aware.