Each Room Processor contains, by default, a main preset (a Toggle preset) that cannot be deleted. This preset is activated whenever the room comes off the shelf (in other words, whenever the wall configuration results in the room being in use). You can read more about this main preset here.
In addition to the main preset, you can create additional custom presets for a specific room. Let's say the room's configuration can change depending on how it is being used (for example, the head table where a panel of speakers is seated may move about depending on the current needs). In this situation, you could create presets for each possible arrangement.
Adding items to a Room Processor preset via drag and drop or updating existing items in the preset using the update buttons can only be performed when the associated Room Processor is currently in use. This restriction is in place to prevent accidental changes to link states that could result in unintended behaviors of linked remotes as room processors are activated or deactivated.