You can restore to the previous version using the Restore button if you have the @baseclass.ToolbarFull privilege.
Note: Use the Restore button when a deleted rule instance has to be recovered.
Do not use the Restore operation to fall back to a rule instance available in a lower-numbered version. Use the Delete toolbar button to delete the current higher-numbered version or versions that mask or override a lower-numbered version.
If you want to change the lower numbered version but the version is locked, use Save As, not Restore, to copy or promote an older version to the current unlocked higher version.