If you want to reset or change your password either way you just click here
https://cockpit.branchbob.com/login. If you then hit the "Kennwort vergessen/password forgotten" button you will be invited to type in your mail address. Within a few minutes, you should find a new email from branchbob in your mailbox with which you can reset your old and save your new password.
If there is no mail you should probably take a look at your spam folder.