which is the easiest way to get from Stone Forest to Kunming railway station?

You can take a coach from the scenic area to Kunming East Coach Station first. I remember that the last schedule is at 20:00. You need to confirm the information when you arriving there.
After arriving, take metro line 3 to Dongfeng Square and transfer to metro line 2 to South Huancheng Road. Then take metro line 1 to the railway station.