If you are main account administrator, you can switch workspace in two ways\

1. Using Top level Workspace menu

2. Workspace list available in account settings menu 

If you quickly want to switch the workspace, simply click on the Workspace icon on the top-right side and you will see list of workspace created/available. Click on the desired workspace name and you will be switched to it. 

Alternatively, if you have admin role, you can move over to Account Settings > Workspace, you will see list/cards of all available workspaces. Hovering a mouse over the desired workspace card will display button 'Go to workspace'. Clicking on this button will switch your workspace to it.