I went through the Hybrid Setup configuration, unaware that this would enable DirSync. I now want to disable AD synchronization again.
When I go to the Azure AD Admin Center and disable directory synchronization for our domain, the switch will go back to Activated right after it was deactivated.
I also tried disabling DirSync through PowerShell:
Set-MsolDirSyncEnabled -EnableDirSync $false -Verbose
This only results in the unhelpful error message:
Set-MsolDirSyncEnabled : You cannot turn off Active Directory synchronization.
After DirSync has been enabled for a domain, it can take up to 24 hours until you're able to disable it again.
In our specific case, we were able to disable it after approximately 12 hours.