A Symphony chat room cannot be deleted by a user or an administrator for compliance reasons. It can only be deactivated by the owner of the room and then locked by Compliance Officers. Refer to the Knowledge Article found here on how to deactivate a chat room.
When a chat room is deactivated, all users will no longer be able to view the content within the chat room or search for the chat room, unless the original owner reactivates it.
When a chat room is locked, it is deactivated and the owner cannot reactivate it unless it is unlocked by Compliance Officer first. Refer to the Knowledge Article found here on how to activate a chat room.