RE01B LDO turns off

Hi.

Is there an application note that explain which is the right way to turn off internal LDO and use external voltage regulators connected to VCL and VCLH?

Also, I have seen in the files r_system_api.c and r_system_api.h (in the r01an5606xx0220-re01b-ble/ble_project_server project) that is missing the protect register PRCR->PRC4 handle. Instead, this handle is available in the RE01 project files (r01an4837_re_power_management_1500kb project).
Is it not possible to turn off LDO on RE01B device?

Thanks in advance.