How can I remove the link between my Nintendo Account and my Nintendo Network ID?

You can remove the link between your Nintendo Account and Nintendo Network ID by going to "Linked Accounts" after signing in to your Nintendo Account.

If you sign in to your Nintendo Account using a Nintendo Network ID, you have to create new Nintendo Account sign-in data before disabling the link. This can be done by linking your Nintendo Account to a different external account or by adding a password to your Nintendo Account. To add a password, select "Password" after signing in.