Is there any way to remove the whole "personal inbox" feature via permissions, or an addon?

Not useful to my community, and I don't want to be responsible for moderating content between users. I have basically cut the ability to private message as much as possible, but I'd still like to be able to easily remove the button and whole inbox feature.

 

 

ACP -> Applications -> click in System to expand. Find Messenger and click in the padlock. Remove selection from all groups.