Why did beatty want montag to wield the flame thrower to destory his own house

He wants Montag to burn his own house down because

1. Montag is forced by Beatty, with the consequence of death

2. Montag is in possession of books, which is in direct violation of the law.

However, Montag feels both angry and joyful at destroying the parlour, which he hated throughout the story.