[Vuejs]-Vue2 how to change the main data component from another single file component?

You can pass data down to child components using props (properties)
https://v2.vuejs.org/v2/guide/components.html#Props

I dont know if this is the best way but i solve my problem using my vue instance like a global variable

vm = new Vue({
...
});

window.vue = vm

and then changing

window.vue.menu = 'MenuInicial';