You can use LeanTween to fade an object, here is an example:
var time:float = 2.0;
var alphaVal:float = 0.0;
LeanTween.alpha(gameObject, alphaVal, time);
Just make sure that the object has a shader that supports transparency! I would recommend Owl Labs Shaders: http://owlchemylabs.com/content/ (Unlit with Alpha);