Currently you are able to watch "Robotech" streaming on Crunchyroll, Funimation Now. It is also possible to buy "Robotech" on Amazon Video, Vudu, Apple TVas download or rent it on Amazon Videoonline.
Robotech is an 85-episode adaptation of three different anime television series made between 1982-1984 in Japan; the adaptation was aired in 1985. Within the combined and edited story, Robotechnology refers to the scientific advances discovered in an alien starship that crashed on a South Pacific island. With this technology, Earth developed giant robotic machines or mecha to fight three successive extraterrestrial invasions.