If you can't disable it, you need a 3 strip aux cord (one with a mic) for headphone listening.
Also, in my car, when I start charging my phone, then use a normal aux cord, voice mate does not pop up.
Easy fix. Go to Settings, general, apps, all, then scroll down to voice mate and disable it.
*this is on lollipop and I'm not sure if it is the same for Kit-kat.