All the workflows that you or your team members have initiated will be shown under the Workflow tab.
You can easily find the workflow that you are looking for by using the various filters provided on the left - by module, by workflow status, by action type and by categories of a particular module.
On the right, there will be workflows shown with various status - whether it has started or not, what the last action was, and by whom the next action is to be taken.
If the workflow is no longer valid, or not in use anymore, you can cancel the workflow: