You don't know if your highlights are chunky, ombre or baby -- you just know you don't want them anymore. Maybe they came out too light, or you tried to do the job yourself with less than elegant results. Regardless -- they need to go. You're best off putting your locks in the hands of a trained professional, because the recoloring of your hair requires skillful color matching and timing.
But you can attempt a fix on your own.
Find a color.
Look for a color that matches the base color of your hair. Now is not the time to change your color completely. You can mix your own hair color by purchasing the dye and a 10-volume peroxide developer -- but only if you're experienced in creating color.
Use a brush to apply the hair color, or toner, to your hair over the highlights -- not to your whole head of hair. Allow the color to penetrate for 10 minutes, and then apply color to your full head and brush it through. Leave it on your whole head for another 10 minutes.
Rinse the color out and treat your hair with a conditioner. Style as usual.
Your hair should be close to its base color -- whether or not that's your natural color -- after this process. How successful the processing is, however, depends on how your highlights were created. If they are bleached in and significantly lighter than your base hue, you may still have some uneven coloring.