Resignation Letter : Want to put my papers within first month only

I joined a startup one month back with a hope that it's a good company and will give me growth as position was also a good position. But once I joined, got to know my manager micromanage a lot, she has a need of power control, she has same experience as me and she doesn't let people take control. Within one month only I have realised I can't work here under her supervision, because she doesn't let me do things as per my way and wants to check each and everything and I can sense she has a problem because I take charge, she wants me to do work which mid level people can do, but she wants to force those things on me. Luckily I have got another job, but I don't know how to quit within a month without being a bad person and just want to quit nicely.