Remove Ok google(Not just the text) topic

I'm not a fan of google feeling the need to listen to everything I say. I did search for this, but all I'm coming up with is people wanting to disable the "Ok google" text on the screen. I'd like to disable to feature all together, but it doesn't seem there is an option anywhere. Am I missing something or do you need a custom rom to get rid of this crap? Thanks guys!