Deleting Previously Published Versions of a Workflow
How to manually delete previously published versions of a workflow.
When published, all Nintex Workflows are stored in a hidden library. Previous versions can be accessed and deleted manually from here.
Navigate to the Hidden Nintex Workflow library: http://YourSiteAndSubsiteURL/NintexWorkflows/ This is a standard SharePoint library with versioning enabled. Each folder in this library represents a publish workflow, within each folder are the individual files that make up the Workflow.
Open the folder that corresponds to the Workflow you need.
Each of the files that make up the Workflow will have a version history attached, simply expands this and delete the version you wish to remove. You will need to do this for each file in the folder.
This should remove the previous versions of the workflow, please note that once deleted these versions will NOT be accessible from the Workflow Designer, and will be lost unless restored from a backup or the site recycle bin. If restored we cannot guarantee that they will function correctly, so we recommend doing this only if there is a strict business requirement to remove the versions entirely.
Please note that this is not strictly necessary in regular day to day operations, as you can choose to block or remove previous versions from the "Workflow Settings" list page.