I'm facing an issue of heating my rog 2 is heating when im not using the phone its temperature is like 37 degree
37C(I assume) is fine. You don't need to worry until it's getting around 45C-50C.
For an idle temprature when you're doing nothing, that's pretty high. For me when the room is cool-ish the temprature stays at around 26-30 on normal use and around 32-34 when my room is warm.
Is the phone warm when you hold it in your hand? If not, then it's very important to know which temperature you're referring too. If it's the CPU, then there's nothing weird at all.