Hi,
Login via SSH as root user and run "adduser accountname" and after that change the password for the new user by running "passwd accountname". After that you should be able to login with your new account.
Concider configuring sudo to meet your privilege requirements. Creating superusers is never a good idea. Instead add normal accounts and use sudo to elevate your permissions only when needed. You can find dozens of helpful sites by simply googling "sudo configuration".
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