You can erase your iPhone without Wi-Fi or cellular data by connecting it to a computer with iTunes (or Finder on macOS Ventura and later). This method allows you to restore your iPhone to factory settings, removing all data and settings.
Here's how:
- Connect your iPhone to your computer using a USB cable.
- Open iTunes (or Finder) on your computer.
- Select your iPhone in the iTunes (or Finder) window.
- Click "Restore iPhone" in the summary section.
Important Note: This process will erase all data on your iPhone, so make sure you have a backup of your important data before proceeding.