If an error occurs with a workflow, or a workflow stops responding when users submit task information, the workflow can be canceled. When you cancel a workflow, the workflow's status is set to Canceled, and all of the tasks created by the workflow are deleted.
You must have the Manage Lists permission to cancel a workflow.
If the list or library that contains the item for which you want to cancel a workflow is not already open, click its name on the Quick Launch.
If the name of your list or library does not appear, click View All Site Content, and then click the name of your list or library.
Point to the document or item that is involved in the workflow, click the arrow that appears, and then click Workflows.
Under Running Workflows, click the name of the workflow that you want to cancel.
On the Workflow Status page, under Workflow Information, click Terminate this workflow now.
Note: If the Terminate this workflow now link does not appear, you do not have the correct permission to perform this task. Contact your administrator if you need to have a workflow canceled.