Currently when you delete a permission scheme within JIRA, there is no backup / copy made of the permission scheme. It is simply removed from JIRA. If JIRA would make a backup / copy of the permission scheme being deleted, this would help Administrators in recovering / rolling back changes. This would work the same way JIRA makes a copy of a Workflow.

Current behavior
Click Delete for permission scheme
JIRA asks if you really want to delete the permission scheme
Click Delete to confirm
Permission scheme is deleted

Requested behavior
Click Delete for permission scheme
JIRA asks if you really want to delete the permission scheme
JIRA indicates that a copy of the permissions scheme will be created
Click Delete to confirm
Permission scheme is deleted
Copy of permission scheme shows up under 'Inactive Permission Schemes' popup