If you need to rebuild the Workflow of your Project, you can delete the Workflow:
1. Open the project.
2. Click [Workflow] tab on the left panel.
3. Click [Delete Workflow] button.
4. Click [Delete] button in the confirmation dialog.
Deleting a workflow will delete tasks inside the project.
Deleting a workflow will not remove collaborators from the project.
Deleting a workflow will not delete files inside the project.