After you've verified that all email is being routed directly to the %BRAND_OFFICE_365_SHORT% mailboxes, and no longer need ...

After you've verified that all email is being routed directly to the %BRAND_OFFICE_365_SHORT% mailboxes, and no longer need to maintain your on-premises email organization or don't plan on implementing a single sign-on solution, you can uninstall %BRAND_EXCHANGE_ONLINE_SHORT% from your servers and remove your on-premises %BRAND_EXCHANGE_ONLINE_SHORT% organization.