Yes.  After you log in, click "my account" at the top left corner, and then click "edit". 

Your user name will appear every time you post an entry. Consequently, you may want to use your full name, case sensitive and with spacing. For example, you may prefer a user name like Jane W. Smith to a strange looking user name like janewsmith.

iMechanica identifies each user account by a number. Everything else of an account can be changed.  In addition to changing your user name, you can change password, email address, personal photo.

You can also add some information about you by clicking "My profile" and "My resume".