Hi,
There are no room console API to limit to chat history other than deleting some items manually by going to Explore tab's items. Currently the entire history gets cleared automatically. If you want to delete some messages now, you would have to subsclass some of the functions inside SimpleChatModel.as.
You can see the clear function for deleting the complete chat history inside SimpleChatModel.as. Basically, you need to delete the nodes and create them again. You can do this using PHP also by using our ServerToServer API to delete and create the nodes.
However, we plan to do some changes to our SimpleChatModel in future which will include allowing users to delete some messages. This will be coming in second half timeframe of year.
Hope this helps
Thanks
Regards
Hironmay Basu