2D platformer wall troubles

I am trying to figure out how to get a cube to be without friction on its' sides but I can't seem to figure it out, I have a behaviour script that I've attached to a basic capsule character to see how I would like it to move about, but when it touches the sides of the prefab it sticks. The cube is slanted somewhat just to give the platform slope, which is probably why the capsule is sticking to the sides. Can anyone help with this?