Using the command line interface (CLI) : execute : execute reset
 
execute reset
The execute reset command allows you to reset the FortiDB system to factory defaults. It disconnects all sessions and restarts FortiDB.
Syntax
execute reset {admin-password | all-settings | data}
where:
commands
Description
admin-password
Reset admin's password to default password.
all-settings
Reset the all settings.
data
Reset the database.
Example
execute reset all-settings