Pretty simple -- I've searched a lot online for ways to delete messages in HipChat via the API, but haven't found anything on how to do it. The only thing I did find was this ticket on the community forums, but it's a few years old and I'm not sure whether this feature is still unavailable. If it is available, how exactly do you do it and where can I find a reference to this in the documentation?
This is a known issue. Untill now, it is not possible to delete HipChat messages via API.
See the issue here.