than this Rollback UPN script will assist.
Now just copy the report csv file that you want to rollback to old UPN from Fix office 365 UPN script & paste it inside the roll back script folder.
All users inside the report will be rolled back to OLD UPN & new report will be placed inside report folder.
Note: Exchange management shell is requirement for running this script as well.
$logs = ".\Logs" + "\" + "Processed_Rollback" + $date1 + "_" + $time + "_.log"
$report = ".\report" + "\" + "Report_Rollback" + $date1 + "_" + $time + "_.csv"