Originally Posted by Gilly

Unsure now if you mean just removing the screw, or removing the bracket once the screw is removed.
Usually the screw is tight but doesn't present a problem to remove it.
Once it's out, like you already tried use some penetrant oil and some light tapping with a hammer to try to break the seal. If you try to pry on it, you could verry well break off one of the "ears" the rotor screws in to, so it's replacement time then. You could also break the lip on the orange colored disc, so you'd want one of those too.
Gilly