How can I clean my complete history?


I would like completely clean my (operational) Nagios installation.
So I would like to clean out all events, loggings and other registration so I can start withouth any history.

I would like to do this without having to install Nagios again, and keep my configuration.
This way my troubled information about availability would be cleaned out and correct …

Is there a simple way to do this, actually to clean out the databases …