Certainly it is not possible for us users to do it. You should write to support@ryzom.com and ask. I am not at all sure, but I doubt it -- then again, CSRs have mysterious powers.
What can be done is to make a new account, do not make any characters in it and then ask the CSRs to transfer your old toons to the new account. This will be a little expensive, since both accounts have to be paid accounts for the CSRs to do this. You could then cancel your old account.
Given that the sign-in name for the account is only used to access things like changing your payment method, I don't see the point. The account name doesn't have to have anything to do with your toon names.
-- Bittty
What can be done is to make a new account, do not make any characters in it and then ask the CSRs to transfer your old toons to the new account. This will be a little expensive, since both accounts have to be paid accounts for the CSRs to do this. You could then cancel your old account.
Given that the sign-in name for the account is only used to access things like changing your payment method, I don't see the point. The account name doesn't have to have anything to do with your toon names.
-- Bittty
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Remembering Tyneetryk
Phaedreas Tears - 15 years old and first(*) of true neutral guilds in Atys.
(*) This statement is contested, but we are certainly the longest lasting.
<clowns | me & you | jokers>