If you prefer to watch how to do this, click on the video below.
Locate the User and click on their Username to access their profile (see view Users if you're unsure how to do this).
Click on the Archive/Restore link from the Common Tasks tab (you can also click on the Details tab followed by the Archive button if you prefer).
You will be taken to a two-step wizard.
Read the warning message.
Click the Archive button.
The LMS will confirm that the User has been Archived.