Cancelling Dependent Pass without being present in Malaysia

I am in a similar situation - except that i am shortening my pass and not cancelling. Which means, I am transferring my employment pass from current company to the new company i am going to join. My wife traveled to India on 17th August. So, I asked my current employer to cancel my wife and son's dependent pass on 18th August. They asked mdec for the process to cancel dependent pass. As per mdec, to cancel the dependent's pass, the employer has to initiate the online cancellation process by submitting the soft copy of the airline ticket or photocopy of the exit stamp in passport. I would suggest you to confirm the same with your employer.
So, to be precise you only need either of the documents (mentioned above) to cancel dependent's pass.

In the Pre-Pandemic days, they used to physically stamp the visa page on the passport as cancelled, so it could be cancelled in the system, but i dont think its possible to cancel the visa without physically presenting the passport to authorities here in MY.

do update your experience once you process your new visa.