Currently, downgrading a PS4 from firmware 13.02 to 9.00 is not possible through standard software updates or simple settings changes.
Firmware 9.00 is the last highly stable jailbreakable firmware. Firmware 13.02 patches all known public entry points, including the BD-JB (Blu-ray Java) used on 9.00 and the PPPwn RCE used up to ~11.00. ps4 downgrade 13.02 to 9.00
Tools Required:
No Simple Software Fix: You cannot simply plug in a USB drive with firmware 9.00 and "reinstall" it over 13.02. The PS4 system prevents installing any firmware version lower than the one currently active. Currently, downgrading a PS4 from firmware 13
The "One-Step" Revert: The PS4 stores firmware in two slots on its motherboard—an active slot (Slot A) and a backup slot (Slot B). You can only revert to the firmware stored in the backup slot. The "One-Step" Revert : The PS4 stores firmware
There is one technical exception known as Firmware Revert, but it is extremely difficult and carries a high risk of "bricking" (permanently breaking) your console.