WARNING! When you factory reset the device, all your personal data located on the phone will be deleted, including ringtones and media files, apps, downloaded content, contacts etc. Furthermore all settings will be restored to factory values but data located on the SD and SIM cards won’t be affected.

NOTE: You can check this thread for a guide on how to back up data, and this thread for a guide on restoring data.

Factory Reset via Settings:

  1. Open “Settings
  2. Go to “Phone Management
  3. Tap “Backup & reset
  4. Tick or clear the check boxes linked with “Automatic restore” and “Back up my data
  5. Tap “Backup account” and select the desired account
  6. Tap “Factory Data reset
  7. Optionally, select to “Erase D Card” too
  8. Tap “Reset phone
  9. In case you have a lock screen set, enter your PIN/password
  10. When ready, tap “Delete all” > “Reset

Factory Reset via Android Recovery:

NOTE: If your phone freezes, crashes, or otherwise prevents you from resetting it using the method above, you can try resetting it from Android Recovery:

  1. First ensure the phone is powered Off
  2. Press and hold “Volume down” and “Power” at the same time
  3. At the LG screen, quickly release and re-press “Power
  4. Release the buttons at the “Factory data reset” screen
  5. Press “Volume down” to navigate the menu and highlight “Yes
  6. Press “Power” to select the highlighted option
  7. At the “Erase all user data and restore default settings” prompt, highlight “Yes” and press “Power” one last time

See More: LG K11: Factory Reset via Settings or Android Recovery