I created a site for my client, and to test it I created many rubbish pages. I also added rubbish content to real pages before adding new pages. I deleted the rubbish pages and content however the data is still available in the administrative area through versioning history.
How can I clear all versioning history so only versions from now on will be preserved?
the only way i know of to dump the versioning history is to empty the database table SiteTree_versions. if you have extended sitetree and added database fields, there will be extra tables like products, products_Live, and products_versions that will contain the extended data, and you could probably dump the data in those extended _versions tables as well.
NOTE::: this will permanently delete all versions and you wont be able to get it back!
I'd test locally before messing with a live site too, so you know what to expect.
oh, and back up the database before you try it too, so you can recover the data if you need.