I want cancel domain mapping or change domain name . iraninfo.n.nu

HI
I sell the domain name ( iraninfo.co.ir ) and set dns to n.nu
this domain not active ....... and domain seller company tell change domain name to other domain name.
i dont reache to my site to change domain name or cancel domain mapping
my site = iraninfo.n.nu
new domain name to set my site = www.netfo.ir

Sorry for late reply, this was done long ago.