I finally found out where the latch is and how to remove them. I feel stupid haha... but I cannot change the wiper arms position because it have a key path and you can only insert the arms in one position. My main problem is when the passenger wiper go to his original position, it go too far down and hit the plastic. In this way, the wiper cannot be warmed by the wind-shield heat in the winter and it always frozen. Can someone already fix this problem ?
2009 Ford F150 Lariat - Window Sticker (link