How do i change my bb not to keep me sent SMS messages and my Sent emails ??????????

You can hide them, or manually delete them.

Hit the delete key. They will be deleted.

Messages --> Options --> General Options --> Hide sent messages (or something to that effect)

It won't delete it though, it will only choose not to show them.

A good tip is to press alt-o. It will show only the outgoing messages. Then you can go to the very top of the list where it shows the date, then click menu, then delete prior.

Other shortcuts that can are cool. (I use them also to help remove messages)
alt-i - incoming messages
alt-o - outgoing messages
alt-s - SMS messages
alt-m - MMS messages

There are others, but those are the ones I use all the time.