Create a support ticket. They'll get some info from you and should be able to get you taken care of.
https://support.presonus.com/hc/en-us/articles/210050813-How-to-create-a-new-Support-Request-
Can't contact the person who originally owned my ATOM to deregister
Annoying as it now stuck in Mardi Gras setting & cant used as regular midi controller for other software... which was purpose of purchasing 2nd hand