Disabling RAM in nRF54L15 and avoiding my application to use RAM sections that I want to power off - nRF Connect SDK

in my application, I need to reduce /disable RAM sections in nRF54L15 to save Idle RAM current.
For Example, I need to retain only 64KB RAM when I am in idle.

how can I avoid my application to not use RAM sections which I plan to disable, and how do I then disable them? (if I simply disable them, without power-down the RAM and preventing my application to use them, I get a crash)

Please point me to documentation and let me know how big blocks I can disable in nRF54L15 (32KB?)

Thanks

BR
LA