To Fully Restart Your Career Mode You Will Need To Follow These Simple Steps:

First head to this link in your folder:
C:\Users\[username]\AppData\Local\Dakar2Game\Saved
(Put your username in the [] brackets)

After, click on the SaveGames folder. Next Delete everything in that folder than get back to the Saved folder.
Next, click on the Logs folder and continue to the NGX folder and again, delete evrything in that folder.

Reload the game and you now have a new career mode!