One way is to do it using API WF_ENGINE.ABORTPROCESS by wrtting a simple script like below…
BEGIN
WF_ENGINE.ABORTPROCESS ('GLBATCH', ' 2949213*847');
-- wf_engine.ABORTPROCESS ('Type Internal Name', 'Item Key');
END;
COMMIT;
Another way which I think is more appropriate than API is to do it from front end… to perform below steps you need to have workflow admin access.
Step 1: Query the workflow and click on ‘Activity History’ button
Step 2: Click on ‘Cancel Workflow’ button
Step 3: Click on ‘Apply’ button
Step 4: Re-query workflow, verify if workflow is cancelled
Step 5: Open ‘Activity History’ and verify if open notification is closed / complete