It resembles someone that used to post on here who when he wanted to become a local politician he wanted all his forum posts deleted so there would be no skeletons in the closet that the local news could discover. though).
If they truly never want to log into NSC again they could change email to an address they don't own.
The visit a password generator site such as https://www.avast.com/en-gb/random-password-generator
Copy the password and change NSC password with the copied password.
Log out of NSC...