He served as the head football coach at Purdue University from 1970 to 1972, compiling a career college football record of 13–18. DeMoss played football as a quarterback at Purdue from 1945 to 1948. He was then selected in the second round of the 1949 NFL Draft by the New York Bulldogs, from whom he played in 1949.
DeMoss was selected again in the 22nd round of the 1950 NFL Draft by the New York Giants, but retired from playing to become an assistant football coach at Purdue.
After his stint as Purdue"s head football coach, DeMoss remained an assistant athletics director as the university until 1992. DeMoss was promoted to head coach in 1970.
DeMoss inherited a Purdue squad who was loaded at the running back position with Stan Brown, and Otis Armstrong, but the team struggled to find consistency out of its quarterback position. DeMoss resigned following the 1972 season, citing his desire to be with his family more as his reason for stepping down.
DeMoss compiled a career college football record of 13–18.