Have you backed up your device in the past and want to restore from a save or do you want to do a complete factory data reset?
The guide says this for factory reset:
"Factory Reset
This may be necessary as a last line of defense when other solutions have failed to rectify one or more issues with a possible software component. Navigate to Setting -> Backup and Reset -> Factory Data Reset. Note that you may select “Back up My Data” prior to doing so. (Optional)"