Azure/Office 365 - Convert from ADConnect to Online Only

When you are ready to turn off DirSync, and all exchange mailboxes are in the cloud, the next steps will be turning off DirSync: 

https://docs.microsoft.com/en-us/microsoft-365/enterprise/turn-off-directory-synchronization?view=o365-worldwide 

You need to connect to MSOL with your global admin credentials: 

connect-msolservice 

Set-MsolDirSyncEnabled -EnableDirSync $false 

Next, you can uninstall AD Connect cleanly: 

https://docs.microsoft.com/en-us/azure/active-directory/hybrid/how-to-connect-uninstall 

Please let me know if you have any additional questions or if you wish to archive your case for now? 

Thank you and have a great day. 

This will switch AAD_AD sync accounts to cloud ONLY accounts.  If sync runs after this it will create duplicate accounts.