The eighth child in a brood of nine, the young Delo loved school. He graduated valedictorian from elementary school, and was the first from Mauban, Quezon to be admitted to the prestigious Philippine Science High School (which he attended for three years, after which he transferred and graduated from another high school). He then entered the Luzonian State University in Lucena City, where he became involved in the university student council and the school organ, The Luzonian, as well as other campus activities. As a child tagging along with an elder sister as she attended political teach-ins, and because of the pervasive discontent with the dictatorship, Manaog imbibed a nationalist outlook early on. He became a Kabataang Makabayan activist while still in PSHS, during the early years of martial law.
Moving to the University of the Philippines in Los Baños in 1977, Manaog joined the staff of the UPLB Perspective. In one article, he tried to make his fellow students understand that it was only right to question the university’s orientation: “Para saan ba ang pasilidad, kagamitan at gusali kung ang programang pang-edukasyon naman ay hindi akma sa kalagayan ng lipunang nangangailangan nito? ... Nagiging manpower supplier tayo sa sistemang lumulukob sa ating ekonomiya.” (What’s the use of these facilities, equipment and buildings if the curriculum is not suited to the conditions of our society? We only serve to supply the manpower for the system that controls our economy.”
His friends were not surprised when he decided to quit school in order to become a full-time labor organizer. “I will never let my schooling interfere with my education,” he declared.
He worked with the National Federation of Labor Unions, and the Institute for Workers Leadership and Development in Laguna. His friends would see him from time to time. They knew he was aware of being under surveillance. But when he did not show up for two months, they began looking for him and also informed his family. They had last seen him inside a grocery store at the UPLB campus on June 21, 1984.
A campaign was organized to look for Manaog. Pickets were held in front of military camps. The military denied any involvement, but Delo's family and friends remain unconvinced. They never found him.