What are my rights to the site design?

Question

Design

Hello. I worked with a person without a contract, on a verbal agreement. More than a month ago, the work was handed over, paid for and transferred to another specialist for layout.
Now they are writing to me to remove the work from my portfolio, they say, after payment, the intellectual property passes to the customer and blah blah blah.
Who is right? How can you protect yourself from such situations in the future? If you work under a contract, then what must be indicated there?

Answer 1

Answer him that copyright is inalienable, he received the full right to use this work (design), and you still have the right to declare that you did it. In order for you not to have this right, it was necessary from the very beginning to work according to the NDA, where the terms of non-disclosure would be prescribed. Offer to sign an NDA now for an additional fee.