As a few people have requested this, I’ve written a .Net sample for managing folder Conversation View settings for OWA 2013.
In Exchange 2013, the Conversation View settings are stored the FolderViewState element of the OWA.ViewStateConfiguration configuration item stored in the associated content of the Root folder.
This sample can be used to list or update the current settings. If the Update view settings checkbox is unchecked the sample will list the settings. When checked, it will either enable or disable Conversation View on all mailbox folders.
To use the sample, first create an ExchangeService object via the Service > Create menu.