Hi,
I have created a on premises Domain Xyz.com also created some users and Sync with office 365 and working fine due to some Hardware crash i have formatted and reinstalled the same xyz.com on premises.Everything is working fine with the new AD and the only problem i am facing is that the Users created with the old xyz.com password reset is not getting sync.
I have created all the users on the new domain but the office 365 users are not deleted at the time of crash and after the new domain it got SYNC and working.