Dying brown hightlighted hair back to its natural colour?

I have mid-brown hair which has been highlighted with a few shades of blonde. i would now like to go back to my natural colour and was planning to do this with a diy kit at home.can i follow the instructions of the box or do i need to prepare my hair for this first - would not want the highlights to show through the redyed colour or for those sections to fade quickly.any advice would be great!
Answer
Leave the colour to grow out or you risk damaging your hair and routes.