The patch is located in Game > Game data > Call of duty 4 (Make sure it's not the savefile as I'm not sure if the patch is in Game data or Save Data)

Once you find it just press triangle and delete it.


If you want to locate the file in Osses then its:
Ps3_Boot/**drive 1/gamefiles/dataG(or dataS)/Callofduty41.30.pkg(or .ps3)

If you want to locate the file in Windows:
**Drive1/Game Data (or Save Data)/packages/Call of duty 4-Patch1.30

If you want to locate the file in RawOS:
Biosmain/int1_**drive1/pack01/game00(01 for save data)/COD4P.130

**Note my drive is renamed to Drive 1