In Salesforce, you will have to manually delete all versions of a Process in the Process Builder before you can remove that Process. If you create a lot of versions, deleting them will become rather tedious work.
This script makes the work simple. You just need to type in the Process name and click a button and all inactive versions of that Process get deleted.
1. Go to the Process Builder page in Salesforce.
2. Refresh the page and you will see a Mass Delete Versions button besides My Processes.
3. Expand the Process you want to delete to see all the versions. They must all be inactive. Otherwise you can't delete them.
4. Click the Mass Delete Versions button and enter the Process label name (not API name).
5. You will see some dialogues asking you to confirm the deletion. Don't click anything. Just wait for it to continue. You may also get some Error dialogue. Wait for a little while and it will be gone. Then you will find the Process has been removed.
If a Process has dependencies, you will have to resolve the dependency before you can delete the Process.