How Can I Destroy User Data After Insertion ?

[eluser]Zeeshan Rasool[/eluser]
Hi all, here is a problem im facing.

Problem is , when i create a new user and click submit button the CREATE_USER_DB function executes and new user has been inserted. But when i refresh the page by pressing F5 or else an other user data is inserted in DB with same record values
How can i destroy userdata or $_POST data so it can be stopped?

Very Thnx in Advance.