No, you do not need to run the Wizard again.
You can simply change the MX record
Assuming that you have already moved all of the mailboxes to Exchange Online, you can point the MX and Autodiscover DNS records to Exchange Online, instead of to on-premises. For more information, see External Domain Name System records for Office 365.
Make sure to update both the internal and external DNS, or you may have inconsistent client connectivity behavior.