How to deregistrar an UNCODE theme license ?

I want to deregistrar a productt license , but impossible to find where on ENVATO website, is it about to force us to buy a new license ?

Envato terms are clear in that matters, one website = one license and it’s not transferable.
If you’re changing the domain, you may need to purchase a new license.

Although, some authors are OK to change the domain, you may contact the author for the further information/support.