Add & Remove Custom layers into 3D Models

Hi everyone, I am trying to dynamically change layers of 3D models using script . adding works fine. But removal of the same is not seems to be working fine. i.e. When tutorial for Coin is clicked I am adding custom layer to the coins again clicking on same button I removes the tutorial screen That Time I want to remove the layer which I added just before that. Same way it should work for Obstacle tutorial also.
Can anyone look into this repo : PlayCanvas | HTML5 Game Engine
Thank you