How can I log out of fortnite on the switch?

I want to change my account name but I don't know the password of my account anymore and I don't have the email address anymore. How can I log out to create a new account

For this you have to look in the settings under Account. You can then log out there.

I can't find a button to unsubscribe I've looked through everything

Go to the Epic Games website and unlink your nintendo account.

Read the question correctly, I no longer have my account information!

If you had pressed "stay logged in", you would have no problem now.

Write to Epic Games and change your email. I already did that too.