A factory reset, also known as a hard reset, erases all the data and settings on your iPhone or iPad, and restores it to its original state. Here’s how to perform a factory reset:

1. Backup your iPhone or iPad. Before performing a factory reset, it’s important to backup your device to ensure that you don’t lose any important data. You can backup your device using iCloud or iTunes.

2. Go to Settings > General > Reset.

3. Select Erase All Content and Settings.

4. If you have a passcode or Restrictions enabled, you’ll be prompted to enter it.

5. Tap Erase iPhone/iPad.

6. Enter your Apple ID password to turn off Find My iPhone/iPad.

7. Tap Erase.

Your iPhone or iPad will now reset and erase all data and settings. The process may take several minutes to complete. Once the process is complete, you’ll be taken to the setup screen, where you can set up your device as new or restore it from a backup.

Note that once you perform a factory reset, all your data and settings will be permanently deleted and cannot be recovered. Therefore, it’s important to backup your device before performing a factory reset.