Firing your wedding planner

I'm done with my wedding planner and I want to end our contract. I still owe $400 to her out of the $1200 I've already paid her. I rather cut my losses now than to keep her around and be miserable at my wedding.

She's done zero for my wedding yea it's in September but still you should be helping me out planning that's what I've hired you for. I sent her the colors that I've chosen for my wedding (Blush Rose Gold & Navy) and then how I'm thinking about doing my reception tables and she told me that I shouldn't use blush or navy tablecloths and put those colors together because it'll look like a baby shower💬🤔🤷
Clearly, my family and friend's will know they're at my wedding and not a damn baby shower.

Just another thing this lady says that rubs me the wrong way I rather cut my losses and fire her and move on and I'll just do this by myself like I have been from get go💁

So how do I go abouts on firing this lady. Do I need to write up a letter and email it to her do I schedule an appointment with her and say why I'm firing her and say ✌