Typically, workflows seldom have to be removed from a project, but if the need arises, they can be deleted in limited cases. This article describes how you can delete an existing workflow. 

Prerequisites

• You must have "Change" access rights to the CMS project OR the Administrator role in the server.

If a workflow is not assigned to an Issue Type, it can be deleted. Right-click on the Workflow and select Delete workflow. 

A workflow that is or has been in use, i.e., used by issues in a project, cannot be deleted. If you try to delete it, you will receive a message that it cannot be removed.

Instead, replace it with a new workflow to meet your needs or modify the existing one.