Manual deletion is pretty straight forward.
Log in, edit page, select "versions" from tool bar, use check off in front of the old versions you no longer need, select "Remove".

(sorry... just realized you were asking if it could be automated)

Thank you, that if I can do but I'm interested in automatically delete older versions or concrete5 not think those versions.

I believe someone created a custom job which you could run as a cron task periodically to clean out old page versions...

Just did a bit of search through the forums and found this:http://www.concrete5.org/community/forums/usage/delete-pages-after-...

That may be a good place to start if you want to try coding something yourself. You're right though, that would be a handy feature to have built in to keep things more cleaned up.

Asked the question of turning off versioning with C5 core team in their live Totally Random show and they have said that it is not possible.

You can go and delete old version through versioning popup for the page from either edit mode or the site map, but that is the only way... currently.

They did mention that a while ago someone posted about a way you can do a tidy on old page versions, which I think triplei found for you.