You can change your Nominated Account via Internet Banking if you have 15 days or more before maturity.
If there are less than 15 days before maturity, you will need to let it mature into a Matured Funds Access Account (or Matured Funds Access ISA if you have a Cash ISA) before you can change your Nominated Account. This is due to security restrictions in place to protect your account.
Once your funds are in a Matured Funds Access Account (or Matured Funds Access ISA), you can log into Internet Banking, change the Nominated Account and close the account.