It has two lock latches, which lock in an identical way to the radiator cap. Even that takes a 180 degree turn, these latches need a 90 degree turn to lock them up in the right place.
There are two support mounts which face the firewall and go in certain plastic clips to secure the other end of the plastic cover. Generally, it houses most of the electrical components, usually aftermarket ones.
The thing that fell onto the accelerator pedal must be the shock sensor installed with your steelmate, or probably the steelmate unit itself
In short, you can't get rid of the plastic covering unless you get rid of all that junk up there.