|group_index||The group index to be destroyed.|
Audio sync groups need to be destroyed when not in use to free
up the memory and sound resources associated with them using this
function. It takes the group index as returned when the group was
created using the function audio_create_sync_group(),
and frees all resources used by the group.
The above code destroys the sync group indexed in the variable "sg", and would probably be used in the destroy or Room End events.