Things You'll Need
Instructions
Turn on your Wii gaming system. Insert "Wii Fit." Navigate to the Wii Fit Plaza.
Select the Mii you wish to delete. When you click on the Mii, user settings for the Mii will appear over its head. From that list, choose "Delete User Data," and then choose "Yes."
Delete a password-protected Mii by first guessing the password several times. You will eventually be prompted to enter the height of the user who created the Mii. When you correctly do this, you will be allowed to change the password or remove password protection.
After you have gotten beyond the password protection in Step 3, then complete Step 2.
With space now available for a new Mii, simply create the Mii you want as you have done with the other Miis you have created for the game.