Kristian James Samuel White is awaiting sentencing over his use of a stun gun on great-grandmother Clare Nowland in a nursing home in southern New South Wales in May 2023.
He was found guilty of manslaughter by a jury last Wednesday, prompting Commissioner Karen Webb to dismiss the senior constable yesterday.
"I have determined that I do not have confidence in the officer's suitability to continue as a police officer," she said in a statement.
Before telling the public, Ms Webb spoke with Mrs Nowland's family to notify them of the decision.
The family criticised the speed of the decision to "finally" terminate the 34-year-old's employment.
White had been suspended from duties with pay during his trial but was removed from the payroll a day after his guilty verdict.
"The Nowland family consider the decision to be too little, too late where the commissioner has had full access to all materials on which the jury last week found Mr White guilty of the unlawful killing of Clare for over 12 months and chose to take no action," lawyer Sam Tierney said on the family's behalf.
The jury was told Mrs Nowland had symptoms of dementia so severe she would have been unable to comply with orders barked at her by White before being fatally tasered.
Police and paramedics were called to Mrs Nowland's nursing home after the diminutive nonagenarian grabbed two steak knives from a kitchen and raised them against residents and staff before throwing one at a carer.
White pulled the Taser's trigger after only three minutes of negotiations to get her to put down the remaining knife.
He was heard in video footage played at his trial saying "nah, bugger it" before shooting Mrs Nowland in the torso.
She hit her head on the floor as she fell and died at Cooma Hospital a week later.
"He never intended for Mrs Nowland to be harmed or injured," White's lawyers said after the jury's verdict.
"He has never lost sight of the fact that Mrs Nowland passed away and he is acutely aware that the Nowland family is deeply hurt by what happened."
White remains on bail after a failed crown detention application.
His sentence hearing is expected to be held in February.
