Typically, workflows seldom have to be removed from a project, but if the need arises, they can be deprecated and, in limited cases, deleted. This article describes how you can deprecate or delete an existing workflow.
Deprecating a 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, the solution is to deprecate the workflow. Select the workflow and check Deprecated.
A deprecated workflow cannot be assigned to an issue type. You can reactivate a workflow at any time, by unchecking the Deprecated box.
Deleting a Workflow
If a workflow is not assigned to an Issue Type, it can be deleted. Right-click on the Workflow and select Delete workflow.