Your Apple ID will always show your past purchases. If you really want to hide them, you need to make a new Apple ID which will not have any associated with it. You will not be able to get previous purchases on the "old" Apple ID on the new Apple ID though.
“If you are neutral in situations of injustice, you have chosen the side of the oppressor. If an elephant has its foot on the tail of a mouse and you say that you are neutral, the mouse will not appreciate your neutrality.” Bishop Desmond Tutu