how to downgrade moto g 2nd gen from lollipop to kitkat without root I am having a problem while gaming on my new android update on moto g (2nd gen). So, i want to downgrade the android version please help me out.
A downgrade (as well as an upgrade) can be performed by flashing the corresponding ROM that match your device configuration, that is  MOTO-G (2nd Gen.)

So, first thing is to find Appropriate ROM for your device MOTO-G.(2nd Gen.)
You may find more hints at this LINK.

Once you find the ROM, you can downgrade(or upgrade), as needed. Refer rom-flashing for more details and instructions related to ROM Flashing.