To rename your workspace, open the workspace settings popup by clicking on the workspace name on your home page, or by clicking "Workspace Settings" from the workspace drop down menu in a collection.
You can also click on the three dots next to you work space name inside the panel on the left side of your screen to get to the workspace settings.
Click on the name of the workspace in the top left corner. A cursor will appear at the end. Type in the new name and hit Enter.