Mac software, Os x yosemite versions 10.10.2

Recently updated mac to os x yosemite. When updating, a new user account was unintentionally created. Now, that newly created user account is being "recognized" as the main account [note:on this new account it's as if the computer is starting from the beginning, none of the previous settings or preferences are there, BUT all of the information is still on the computer]. Even at log-in the original user account is not there to log-in to. How do we get the original user account to once again become the main user account i.e. when the computer is restarted and the log-in window is presented, the original user account will be there to log-in to?

Thanks in advanced