Rehúso is the first-person conjugation of the verb rehusar, meaning "to refuse". It's a powerful and dramatic word that expresses a strong unwillingness to do something, much more forcefully than just saying "no quiero" (I don't want to).
In this emotional song, the singer is heartbroken and can't let go of his past love. He sings, "Me rehúso a borrar los recuerdos que tengo contigo" (I refuse to erase the memories I have with you), capturing his desperate and defiant feeling of holding onto the past.
Ever been so heartbroken that your phone's storage is completely full because you refuse to delete a single picture of your ex? That is exactly the kind of modern breakup drama Grupo Frontera and Ke Personajes bring to life in "OJITOS ROJOS" (Red Eyes). Right from the start, the singer declares himself a "soldado caído" (fallen soldier) with a shattered heart, openly begging to know if his former partner cries until their eyes turn red ("se te ponen todos rojos") whenever someone brings up their past.
Even though the ex has already moved on to someone new ("Aunque estés con otro" / "Even though you're with someone else"), he is in total denial. He still keeps their contact saved with a special heart and a shared photo, convinced that a phone call will eventually come because they are meant to be together. It is an honest, relatable look at how hard it is to let go when your memories—and your camera roll—refuse to clear space for anyone else.