How Do I Revoke User Access From My Workspace?

You will need to be an Administrator to revoke access / remove invited users from your workspace.

As an Administrator, click on your username on the top-right corner and select "Account Management."

From the Account Management page, locate and click on the "User Administration" button:  

Identify the active user you wish to remove (whose access you wish to revoke) from your workspace, and click on the "slide-out" icon next to the name (illustration below):

From the slide-out, click on "Revoke Access" to remove an invited user's access to your workspace.