What do I change a user account name?

This question arose from activity associated with this question which means that it is related to idiosyncrasies of Time Machine (TM) data restoration.

Thanks to help received from this forum I was able to restore data from a TM backup. However, when TM did the restoration it created a new user account on the target machine, which seems to have all of the properties of the account on the machine on which the backup was created. This includes the password, which causes me to speculate about what other unintended data was transferred to the new machine. The result is that I have the data on the new machine but with the wrong name for the user account. Fortunately, in my situation, there is no data yet associated with the intended user account on the new machine. If I needed to merge the data a different problem would arise. I'll leave that for another day unless there is something I should know to do address my present problem. Therefore, I'm thinking that I should be able to undertake a rename procedure to establish the new account with the intended name but my lack of expertise on OSX makes this what might be called a crap shoot and I'd appreciate getting some advice from people in the know regarding the proper approach (i.e., how the design of OSX intends to deal with such).

To start with it looks to me like the login account name is the name of the sub-directory of ./users that corresponds to the home directory. For example, if I change that directory name the name used for login changes to it. However, it appears as though you can only change that name when you are logged in on a different account. This causes me to think that I must create a temporary administrator account to use for that purpose. This all seems rather convoluted which makes me think that I've failed to figure out how to perform some basic administration procedures. If someone can straighten me out it would be appreciated.