You can usually only revert to the immediately preceding firmware version (e.g., from 13.02 back to 13.00), not skip back several years to 9.00.
Developers are constantly looking for holes in newer firmware. While 13.02 is very new, an exploit for a version closer to yours (like the recent 11.00 exploit) may eventually be discovered. ps4 downgrade 13.02 to 9.00
If you have accidentally updated your console to 13.02, you are likely searching for a way to go back to 9.00. Here is the hard truth you need to understand before reading further. You can usually only revert to the immediately
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. If you have accidentally updated your console to 13