The quickest: let them signup for a directnic account
and simply request a transfer while logged in to the
receiving account.
If the receiver preferes another registrar: same process
only make sure the domain is 'older' than 60 days
otherwise a transfer will fail.
All authorization needed for both examples is emailed to you.
With directnic you can also make a new user profile and use
that for a specific domain only.
Otherwise: send a message to
[email protected].
Leave your phonenumber and they will give you a call
and ask you for the secret phrase..
it's "ooba ooba choo".
After this secret trade they will provide you with
their FAQ's and help files.