A Workflow contains a group of Projects where all the Stories in those Projects share the same workflow. Every newly-created Clubhouse Workspace has one default Workflow that can be customized out of the box, and adding additional Workflows is optional.
To check whether any Projects are a part of a particular Workflow, go to Settings > Workspace Features > Workflows.
In the Workflows Settings menu, Click Edit Team/Projects for the Team you need to delete. This menu will show any remaining Projects in the Team (including those that have been archived). You'll need to either delete or move these Projects before proceeding.
Once all Projects have been moved or deleted, click on the trash can icon next to the Update Team button. You'll be asked to confirm that you want to delete the Team; if so, click OK.
You'll see a pop-up confirming that the Workflow has been deleted, and it will disappear from the Teams list.