The Dash has two factory reset options:
This option allows users to reset all user settings and ride profiles to the preset default settings while retaining any existing workouts, courses, and maps saved to the Dash.
To restore the Dash to its preset default settings:
This option should only be used if intending to erase ALL personal data, activity files, workouts, courses, and other settings.
To completely erase all personal data from the Dash:
WARNING: This option will completely erase all user data and files.