You need to first remove all the users from O365, then use the filter to sync the specific users.
--Disable DirSync, delete all the synced users permanently in O365
--Enable DirSync, use the filter to sync the users.
You need to first remove all the users from O365, then use the filter to sync the specific users.
--Disable DirSync, delete all the synced users permanently in O365
--Enable DirSync, use the filter to sync the users.