The original PSP (PlayStation Portable) does not store a traditional browsing history like modern browsers. Its NetFront browser was minimalistic and lacked a persistent history database, cache viewer, or "clear history" menu.
/PSP/SYSTEM or /PSP/COMMON folders.GAME, SAVEDATA, COMMON, SYSTEM.GAME, corrupt saves in SAVEDATA).If your goal is privacy before selling the device, a full Format Memory Stick + Restore Default Settings (Settings → System Settings) is the most thorough method.