Modern workstations like the ZBook G5 store BIOS passwords in non-volatile memory (specifically EEPROM or SPI Flash chips). This memory retains data even without power. Removing the CMOS battery will reset the system clock and boot settings, but it will not reset the password. The password is burned into the chip's memory.
Historically, HP provided a specialized file (often called an file) to authorized users to clear BIOS passwords. HP Support Community The Process hp zbook 15 g5 bios password reset free
A proven method for many HP business laptops (EliteBook, ZBook) up to 2019-2020 involves: Modern workstations like the ZBook G5 store BIOS