While it’s true that casual employees can be dismissed without notice, they can’t just be let go without following the correct procedures. I worked in retail for years and the way the company dealt with getting rid of people was to just decrease the amount of hours they got. If they wanted to actually sit someone down and say ‘you’re fired’, they needed to have followed all of the procedures, such as giving them written warning and putting them on improvement plans. Without that, the worker was fully within their rights to file for unfair dismissal. So before doing anything on behalf of your shitty boss, I would make sure that the procedure has been followed to a t. If any step is missing, or they’ve never given them a written warning (written, as well. Not verbal. There’s no paper trail for verbal), etc, then you wash your hands of that situation. Because if they choose to escalate it, it’s your ass that’s on the line, not your boss’s.

Are you even in an official managerial position that allows you to dismiss people?