Migration Manager for Active Directory

Do I need Directory Synchronization if after migrating a set of users to Target domain I disabled them on Source domain?

Do I need Directory Synchronization if after migrating a set of users to Target domain I disabled them on Source domain?

I am planning to migrate in small groups of users, and disable each set migrated on source, I am not sure if I need to have Directory synch on or do I even need Dir sync?

Thank you,