shutting down "spare" Cortex-M4

I've taken over this project that is using the STM32h755 CPU. The software is not currently using the Cortex-M4 processor inside the chip. I'm reworking the software so that it will be able to use it sometime in the future. But, until then, I was hoping to "turn off" the M4 to save power.

I think there is something about disabling the clocks in the RCC register for the M4 cpu. But, uncertain as if that is the propery way to go about this.

I could references to software or places in the documentation.

Thanks.