Workflow Deactivation
First you need to deactivate the active workflow, for that you need to go to select action menu and select the deactivate option and after that need to select the disable option.If any ticket is there in that workflow system will show a message so you required to stop the flow for that ticket.
You can go to the Workflow administration application to stop the flow for that ticket. Then you allowed activating a new revision of the workflow.