You can’t delete a workflow in Workflow Administration > Workflow Designer after that workflow has been run at least once. In this case, the Delete button in the toolstrip is grayed-out when you select the workflow.
To delete a workflow that hasn’t been run yet:
- Go to Workflow Administration > Workflow Designer.
- Select the workflow you want to delete.
- Click Delete.
- When prompted, click OK to proceed.
- Click Save.