#JavaScript, 26 bytes s=>!s.replace(/(.)\1/g,``) [Try it online!](https://tio.run/##JcRBDkAwEADAr7RObULFA3iFo4PVLsrGNlZ9vw7mMAe8IP6O6WkuDljWvkg/aHE3JgKPpjXOTl271fNsi@dLmNARb2Y11Tjue4wiSv2HwJzzshAhKiWSEiLAeWpdWVs@) ##Recursive Solution, 28 bytes ([x,y,...s])=>x&&x==y&&!f(s) [Try it online!](https://tio.run/##JcSxDYAgEADAVcCCQKJsgFPYGQuUR1HiE18MTo@FV9xuH0vLFdLdneigelPlWNq31VrTpExfhCjGvEJwL0nVBU/CCDriKr1shmHbQiBi7N85xJznOUYAxohSArD2ODhvlKof)