Terminal window keeps popping up

On an iMac, the "Terminal" windows keeps popping up. An incorrect user name keeps appearing at the beginning of the command line.

Is there a way to change the user name that appears on the command line?

Example:
Last login: Wed Jan 31 12:09:12 on nnnnnnn
usernames-imac:~ username$

Go to System Preferences > Users and Groups > right click on your user and select Advanced Options.

The username is pulled from the "Account name" field.