The username of your investment account also serves as your unique account identifier. Unfortunately, this is why the username of your account cannot be changed.
However, if you would like a account with a different user name, you are welcome to open another account with the desired user name. You can re-use all the data such as your (e-mail) address and linked bank account to open a new account. There are no costs associated with opening an additional account. You can open a new account here.
Be aware that all investment accounts are always separated from each other. If you would like to open a new account, this means that you would have to go through all the registration steps again. Unfortunately, we cannot use any information provided in one registration to complete another registration.
Once you have opened a new account and no longer need the old one, you are welcome to request the closure of the account by e-mail. If you would like to have your positions transferred to the new account, you can request an internal transfer (hyperlink internal transfer).