Delta Guard: Apply protection to existing field
Delta Guard provides a simple wizard to migrate your fields to a protected state.
Navigate to Jira Administration → Issues → Delta Guard custom fields
Click Protect field
Select the field you want to protect, choose a history protection option, and click Next:
Make protected - field values history will be available only to entities configured in the permissions settings
Leave public - field value changes made before protection will remain visible to all issue viewers.
Permanently remove- deletes history of field value changes for all issues
Note: This action is irreversible, and history cannot be restored.
Configure field permissions and click Next
Select field configuration for the field and click Create
That’s it! Your field it protected now by Delta Guard.