You do not need to delete cache or history manually in Firefox Focus because it clears everything automatically every time you close the app. But if you want to clear it instantly, just tap the Erase button on the main screen. It removes all browsing data in one step

Firefox Focus is designed to handle this automatically it clears history and cache every time you close the app. If you want to do it manually, just tap the trash icon while browsing and it will wipe everything instantly. Pretty simple compared to regular browsers.