Attaching a hitch to rx350 on 2007 Lexus RX350

The after market hitch is a 6 bolt screw-in. The undercarriage has 4 thin metal scres ends blocking the assemble. What are these screws and how do i remove them?
-Ed email

Asked by for the 2007 Lexus RX350
Best to go to a U-Haul service center that installs hitches and have them install this