Only the registrant is allowed to get a registration amended. That includes having the name transferred to another registrar (hosting service provider) or updating the contact details. So it's important that the right person or organisation is recorded as the registrant. To get the registrant changed, you need to go through your registrar.
How do you get your domain name's registrant changed?
Contact your registrar.
Tip: If your name changes – e.g. because you get married – you have to let us know.
What happens once the change has been made?
Your registrar will arrange everything with us. We'll update our records and send confirmation to your administrative contact's mailbox and to your registrar.
What should you do if the new registrant wants the name managed by another registrar?
Discuss the situation with your registrar. There are two options:
Get the registrant changed, then transfer the domain name.
Transfer the domain name, then get the registrant changed.
To transfer a domain name, you need a unique code number, called a transfer token. If you go for option 1, the new registrant has to get the token from the registrar. With option 2, you'll have to get the token.