Accesing materials array

I have problems when trying to acces and change a single material inside an array of materials

var Mat ;
Mat = renderer.materials;

Mat [3].material=null;

i need to delete that material when a trigger requests it.

Where am i wrong?

or maybe just delete that array index all toghether?

I’m not sure why you would need to remove materials during gameplay. Can you give a bit more detail about what you are doing?

well, i have multiple materials in some objects acting as layers. beeing the last of them a “rust” layer. But since it is a transparent material i realize that i could just make it transparent all the way and that works same way.