The Nintendo Network ID can’t be changed once it’s been created, but you do not need to delete the current ID to start a new one.
To unlink from your Nintendo Account, go to the Nintendo Account website and log in. From there click User info then scroll down until you see Linked accounts. In that section find the checkmark next to Nintendo Network ID so that those are underlined and when hovered over they show an X icon.
Go to https://accounts.nintendo.com Click on “User info” Scroll down and click “edit” Enter the verification code from the email, then submit Enter a new e-mail address Submit
Nintendo Network IDs and Nintendo Accounts are different. An NNID is attached to both Wii U games and 3DS games, while a Nintendo Account has access only to Switch content.
Nintendo Account website: Sign-in and select Change Password
Select Edit in the Change Password section.
Enter your current password, then select OK.
Enter a new password, confirm it by entering it again, and click Submit to change the password.