How to log out from my old device

I dont really wanna "Log out from my old device" I simply want to make a new account. I have my old one logged into Facebook so I dont think I'll lose

any thing. My old account is LVL 16 with 33k, I didn't want to lose it, will I?

Anyway my question is 

"How do I create a new account without losing my old one?"

And I dont really even know how to make a new account. 

Thanks! 🙂