Can I Take My Convertible's Under-brace Off?

Mustang5L5 is absolutely correct. If you were to remove that particular brace/bracket and you then hit a pothole or speed bump or medium dip, you could easily torque or twist the body to the point that no body shop could set it straight again. Even though I can see/feel my 2017 shake when I drive over rough roads we have here in Georgia, it's there to add structural integrity to the body to compensate for it not having a steel roof.