Make a new character or delete your current character and re-create it. This isn't a single player game, that's why there is no "new game" option. You start the game "new" when you make a new character.
Im not sure if you are serious or not but what the hell. This is not played the same as the other Elder Scrolls games. To "restart" you need to create a new character. From there you can choose to make the same character but you will need to delete the old character first if you choose to use the same name. If you have any items from the Settler's pack pre-order bonus or Imperial Edition items, you will need to transfer those items into the bank before you delete the character if you wish to keep those items, otherwise they will be lost forever. Once you create the new character you can go to the bank and get those items back as the bank is linked to your account and not the character themselves. I hope this helps...