Hi, I have been working with JIRA workflows for awhile, and the common understanding is that you can't delete a workflow status from an active workflow, also stated in Atlassian's document:
https://confluence.atlassian.com/adminjiraserver/working-with-workflows-938847362.html#Workingwithworkflows-editingActiveandinactiveworkflows
But by chance while working on a new customer project recently, I saw that my colleague managed to delete a workflow status from an active workflow.
It seems like this is possible when there are no issues residing in that particular status. I managed to reproduce the scenario on my test instance afterwards.
Perhaps the documentation should highlight this point if this is true. Hope someone from Atlassian could take a look.